0001486957-21-000017 | 10-Q | XBRL Viewer

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Cover page - shares	3 Months Ended
Cover page - shares	Mar. 31, 2021	Apr. 29, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-34658
Entity Registrant Name	BWX TECHNOLOGIES, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	80-0558025
Entity Address, Address Line One	800 Main Street, 4th Floor
Entity Address, City or Town	Lynchburg,
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	24504
City Area Code	980
Local Phone Number	365-4300
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	BWXT
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		95,141,155
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001486957
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 57,677	$ 42,610
Restricted cash and cash equivalents	3,071	3,070
Investments	3,827	3,707
Accounts receivable – trade, net	57,999	153,368
Accounts receivable – other	17,572	22,239
Retainages	81,820	55,172
Contracts in progress	497,827	449,176
Other current assets	39,446	44,256
Total Current Assets	759,239	773,598
Property, Plant and Equipment, Net	884,000	816,471
Investments	9,612	9,356
Goodwill	285,992	283,708
Deferred Income Taxes	47,861	49,415
Investments in Unconsolidated Affiliates	74,216	71,806
Intangible Assets	193,015	192,751
Other Assets	97,979	96,398
TOTAL	2,351,914	2,293,503
Current Liabilities:
Bank overdraft	0	88,694
Accounts payable	146,958	184,392
Accrued employee benefits	59,843	89,740
Accrued liabilities – other	91,100	78,028
Advance billings on contracts	99,218	83,581
Accrued warranty expense	6,858	5,292
Total Current Liabilities	403,977	529,727
Long-Term Debt	1,018,265	862,731
Accumulated Postretirement Benefit Obligation	25,506	25,689
Environmental Liabilities	85,889	84,153
Pension Liability	133,423	144,859
Other Liabilities	28,548	28,576
Commitments and Contingencies (Note 5)
Stockholders' Equity:
Common stock, par value $0.01 per share, authorized 325,000,000 shares; issued 127,262,146 and 127,009,536 shares at March 31, 2021 and December 31, 2020, respectively	1,273	1,270
Preferred stock, par value $0.01 per share, authorized 75,000,000 shares; No shares issued	0	0
Capital in excess of par value	159,295	153,800
Retained earnings	1,599,526	1,549,950
Treasury stock at cost, 32,120,991 and 31,698,747 shares at March 31, 2021 and December 31, 2020, respectively	(1,120,146)	(1,095,452)
Accumulated other comprehensive income (loss)	16,290	8,198
Stockholders' Equity – BWX Technologies, Inc.	656,238	617,766
Noncontrolling interest	68	2
Total Stockholders' Equity	656,306	617,768
TOTAL	$ 2,351,914	$ 2,293,503

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	325,000,000	325,000,000
Common stock, shares issued (in shares)	127,262,146	127,009,536
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	75,000,000	75,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock at cost, shares (in shares)	32,120,991	31,698,747

Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenues	$ 528,273	$ 542,208
Costs and Expenses:
Cost of operations	392,806	392,443
Research and development costs	3,116	4,603
Losses (gains) on asset disposals and impairments, net	(8)	0
Selling, general and administrative expenses	58,261	52,958
Total Costs and Expenses	454,175	450,004
Equity in Income of Investees	8,316	6,063
Operating Income	82,414	98,267
Other Income (Expense):
Interest income	132	231
Interest expense	(7,039)	(7,967)
Other – net	16,386	7,917
Total Other Income (Expense)	9,479	181
Income before Provision for Income Taxes	91,893	98,448
Provision for Income Taxes	22,078	22,828
Net Income	69,815	75,620
Net Income Attributable to Noncontrolling Interest	(66)	(121)
Net Income Attributable to BWX Technologies, Inc.	$ 69,749	$ 75,499
Basic:
Net Income Attributable to BWX Technologies, Inc. (in usd per share)	$ 0.73	$ 0.79
Diluted:
Net Income Attributable to BWX Technologies, Inc. (in usd per share)	$ 0.73	$ 0.79
Shares used in the computation of earnings per share (Note 9):
Basic (in shares)	95,303,728	95,412,351
Diluted (in shares)	95,558,863	95,756,372

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 69,815	$ 75,620
Other Comprehensive Income (Loss):
Currency translation adjustments	8,001	(11,940)
Derivative financial instruments:
Unrealized (losses) gains arising during the period, net of tax benefit (provision) of $139 and $(109), respectively	(412)	313
Reclassification adjustment for (gains) losses included in net income, net of tax provision (benefit) of $56 and $(138), respectively	(166)	420
Amortization of benefit plan costs, net of tax benefit of $(157) and $(167), respectively	580	610
Unrealized gains (losses) on investments arising during the period, net of tax provision of $(24) and $(2), respectively	89	(600)
Other Comprehensive Income (Loss)	8,092	(11,197)
Total Comprehensive Income	77,907	64,423
Comprehensive Income Attributable to Noncontrolling Interest	(66)	(121)
Comprehensive Income Attributable to BWX Technologies, Inc.	$ 77,841	$ 64,302

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Tax benefit (provision) on derivative financial instruments, unrealized losses	$ 139	$ (109)
Tax provision (benefit) on derivative financial instruments for reclassification adjustments included in net income	56	(138)
Tax benefit for amortization of benefit plans	(157)	(167)
Tax provision on unrealized gains (losses) on investments	$ (24)	$ (2)

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Capital In Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Stockholders' Equity	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2019		126,579,285
Beginning balance at Dec. 31, 2019	$ 404,112	$ 1,266	$ 134,069	$ 1,344,383	$ (7,448)	$ (1,068,164)	$ 404,106	$ 6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	75,620			75,499			75,499	121
Dividends declared	(18,254)			(18,254)			(18,254)
Currency translation adjustments	(11,940)				(11,940)		(11,940)
Derivative financial instruments	733				733		733
Defined benefit obligations	610				610		610
Available-for-sale investments	(600)				(600)		(600)
Exercises of stock options (in shares)		56,431
Exercises of stock options	1,332	$ 1	1,331				1,332
Shares placed in treasury	(25,076)					(25,076)	(25,076)
Stock-based compensation charges (in shares)		252,943
Stock-based compensation charges	3,102	$ 2	3,100				3,102
Distributions to noncontrolling interests	(127)							(127)
Ending balance (in shares) at Mar. 31, 2020		126,888,659
Ending balance at Mar. 31, 2020	$ 429,512	$ 1,269	138,500	1,401,628	(18,645)	(1,093,240)	429,512	0
Beginning balance (in shares) at Dec. 31, 2020	127,009,536	127,009,536
Beginning balance at Dec. 31, 2020	$ 617,768	$ 1,270	153,800	1,549,950	8,198	(1,095,452)	617,766	2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	69,815			69,749			69,749	66
Dividends declared	(20,173)			(20,173)			(20,173)
Currency translation adjustments	8,001				8,001		8,001
Derivative financial instruments	(578)				(578)		(578)
Defined benefit obligations	580				580		580
Available-for-sale investments	89				89		89
Exercises of stock options (in shares)		61,260
Exercises of stock options	1,517	$ 0	1,517				1,517
Shares placed in treasury	(24,694)					(24,694)	(24,694)
Stock-based compensation charges (in shares)		191,350
Stock-based compensation charges	3,981	$ 3	3,978				3,981
Distributions to noncontrolling interests	$ 0							0
Ending balance (in shares) at Mar. 31, 2021	127,262,146	127,262,146
Ending balance at Mar. 31, 2021	$ 656,306	$ 1,273	$ 159,295	$ 1,599,526	$ 16,290	$ (1,120,146)	$ 656,238	$ 68

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in usd per share)	$ 0.21	$ 0.19

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 69,815	$ 75,620
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	15,897	15,614
Income of investees, net of dividends	(2,414)	(1,929)
Recognition of losses for pension and postretirement plans	737	777
Stock-based compensation expense	3,981	3,102
Other, net	1,168	283
Changes in assets and liabilities, net of effects from acquisitions:
Accounts receivable	96,449	(2,092)
Accounts payable	(12,623)	(21,158)
Retainages	(26,475)	(15,760)
Contracts in progress and advance billings on contracts	(29,541)	(35,941)
Income taxes	17,134	20,332
Accrued and other current liabilities	1,751	(8,073)
Pension liabilities, accrued postretirement benefit obligations and employee benefits	(42,584)	(36,761)
Other, net	5,119	(461)
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES	98,414	(6,447)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(101,932)	(64,768)
Acquisition of business	0	(16,174)
Purchases of securities	(1,384)	(1,511)
Sales and maturities of securities	1,252	3,680
Other, net	32	0
NET CASH USED IN INVESTING ACTIVITIES	(102,032)	(78,773)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings of long-term debt	205,800	214,000
Repayments of long-term debt	(50,800)	(97,607)
Payment of debt issuance costs	0	(1,340)
Repayment of bank overdraft	(88,694)	0
Repurchases of common shares	(20,007)	(20,000)
Dividends paid to common shareholders	(20,322)	(18,596)
Exercises of stock options	1,672	1,254
Cash paid for shares withheld to satisfy employee taxes	(4,687)	(4,998)
Other, net	(3,680)	5,068
NET CASH PROVIDED BY FINANCING ACTIVITIES	19,282	77,781
EFFECTS OF EXCHANGE RATE CHANGES ON CASH	(542)	(1,419)
TOTAL INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AND CASH EQUIVALENTS	15,122	(8,858)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	48,298	92,400
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AND CASH EQUIVALENTS AT END OF PERIOD	63,420	83,542
Cash paid during the period for:
Interest	11,438	14,668
Income taxes (net of refunds)	4,386	1,327
SCHEDULE OF NON-CASH INVESTING ACTIVITY:
Accrued capital expenditures included in accounts payable	$ 25,849	$ 15,433

Basis of Presentation and Significant Accounting Policies

3 Months Ended

Mar. 31, 2021

Accounting Policies [Abstract]

Basis of Presentation and Significant Accounting Policies

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES

We have presented the condensed consolidated financial statements of BWX Technologies, Inc. ("BWXT" or the "Company") in U.S. dollars in accordance with the interim reporting requirements of Form 10-Q, Rule 10-01 of Regulation S-X and accounting principles generally accepted in the United States ("GAAP"). Certain financial information and disclosures normally included in our financial statements prepared annually in accordance with GAAP have been condensed or omitted. Readers of these financial statements should, therefore, refer to the consolidated financial statements and notes in our annual report on Form 10-K for the year ended December 31, 2020 (our "2020 10-K"). We have included all adjustments, in the opinion of management, consisting only of normal recurring adjustments, necessary for a fair presentation.

We use the equity method to account for investments in entities that we do not control, but over which we have the ability to exercise significant influence. We generally refer to these entities as "joint ventures." We have eliminated all intercompany transactions and accounts. We present the notes to our condensed consolidated financial statements on the basis of continuing operations, unless otherwise stated.

Unless the context otherwise indicates, "we," "us" and "our" mean BWXT and its consolidated subsidiaries.

Reportable Segments

We operate in three reportable segments: Nuclear Operations Group, Nuclear Power Group and Nuclear Services Group. Our reportable segments are further described as follows:

•Our Nuclear Operations Group segment manufactures naval nuclear reactors for the U.S. Naval Nuclear Propulsion Program for use in submarines and aircraft carriers. Through this segment, we own and operate manufacturing facilities located in Lynchburg, Virginia; Barberton, Ohio; Mount Vernon, Indiana; Euclid, Ohio; and Erwin, Tennessee. The Lynchburg operations fabricate fuel-bearing precision components that range in weight from a few grams to hundreds of tons. In-house capabilities also include wet chemistry uranium processing, advanced heat treatment to optimize component material properties and a controlled, clean-room environment with the capacity to assemble railcar-size components. The Barberton and Mount Vernon locations specialize in the design and manufacture of heavy components inclusive of fabrication activities for submarine missile launch tubes. The Euclid facility fabricates electro-mechanical equipment and performs design, manufacturing, inspection, assembly and testing activities. Fuel for the naval nuclear reactors is provided by Nuclear Fuel Services, Inc. ("NFS"), one of our wholly owned subsidiaries. Located in Erwin, NFS also downblends Cold War-era government stockpiles of high-enriched uranium.

•Our Nuclear Power Group segment fabricates commercial nuclear steam generators, nuclear fuel, fuel handling systems, pressure vessels, reactor components, heat exchangers, tooling delivery systems and other auxiliary equipment, including containers for the storage of spent nuclear fuel and other high-level waste and supplies nuclear-grade materials and precisely machined components for nuclear utility customers. BWXT has supplied the nuclear industry with more than 1,300 large, heavy components worldwide and is the only commercial heavy nuclear component manufacturer in North America. This segment also provides specialized engineering services that include structural component design, 3-D thermal-hydraulic engineering analysis, weld and robotic process development, electrical and controls engineering and metallurgy and materials engineering. In addition, this segment offers in-plant inspection, maintenance and modification services for nuclear steam generators, heat exchangers, reactors, fuel handling systems and balance of plant equipment, as well as specialized non-destructive examination and tooling/repair solutions. This segment is also a leading global manufacturer and supplier of critical medical radioisotopes and radiopharmaceuticals for research, diagnostic and therapeutic uses.

•Our Nuclear Services Group segment provides various services to the U.S. Government including nuclear materials management and operation, environmental management and administrative and operating services for various U.S. Government-owned facilities. These services are provided to the U.S. Department of Energy ("DOE"), including the National Nuclear Security Administration ("NNSA"), the Office of Nuclear Energy, the Office of Science and the Office of Environmental Management, and NASA. Through this segment we deliver services and management solutions to nuclear and high-consequence operations. A significant portion of this segment's operations are conducted through joint ventures. This segment also develops technology for a variety of applications, including advanced

nuclear power sources, and offers complete advanced nuclear fuel and reactor design and engineering, licensing and manufacturing services for new advanced nuclear reactors.

See Note 8 for financial information about our segments. Operating results for the three months ended March 31, 2021 are not necessarily indicative of the results that may be expected for the year ending December 31, 2021. For further information, refer to the consolidated financial statements and notes included in our 2020 10-K.

Divestiture of U.S.-Based Commercial Nuclear Services Business

On May 29, 2020, our subsidiary BWXT Nuclear Energy, Inc. divested its U.S.-based commercial nuclear services business, a component of our Nuclear Services Group segment. In a cashless transaction, we exchanged net assets totaling $18.0 million, consisting primarily of property, plant and equipment and certain warranty obligations, for a manufacturing facility and the associated land of approximately the same value. The acquired assets are reported as part of the Nuclear Services Group segment.

Recently Adopted Accounting Standards

There were no accounting standards adopted during the three months ended March 31, 2021.

Contracts and Revenue Recognition

We generally recognize contract revenues and related costs over time for individual performance obligations based on a cost-to-cost method in accordance with FASB Topic Revenue from Contracts with Customers. We recognize estimated contract revenue and resulting income based on the measurement of the extent of progress toward completion as a percentage of the total project. Certain costs may be excluded from the cost-to-cost method of measuring progress, such as significant costs for uninstalled materials, if such costs do not depict our performance in transferring control of goods or services to the customer. We review contract price and cost estimates periodically as the work progresses and reflect adjustments proportionate to the percentage-of-completion in income in the period when those estimates are revised. Certain of our contracts recognize revenue at a point in time, and revenue on these contracts is recognized when control transfers to the customer. The majority of our revenue that is recognized at a point in time is related to parts and certain medical radioisotopes and radiopharmaceuticals in our Nuclear Power Group segment. For all contracts, if a current estimate of total contract cost indicates a loss on a contract, the projected loss is recognized in full when determined.

Provision for Income Taxes

We are subject to federal income tax in the U.S. and Canada as well as income tax within multiple U.S. state jurisdictions. We provide for income taxes based on the enacted tax laws and rates in the jurisdictions in which we conduct our operations. These jurisdictions may have regimes of taxation that vary with respect to nominal rates and with respect to the basis on which these rates are applied. This variation, along with the changes in our mix of income within these jurisdictions, can contribute to shifts in our effective tax rate from period to period.

Our effective tax rate for the three months ended March 31, 2021 was 24.0% as compared to 23.2% for the three months ended March 31, 2020. The effective tax rates for the three months ended March 31, 2021 and 2020 were higher than the U.S. corporate income tax rate of 21% primarily due to state income taxes within the U.S. and the unfavorable rate differential associated with our Canadian earnings. Our effective tax rates for the three months ended March 31, 2021 and 2020 were favorably impacted by excess tax benefits recognized related to employee share-based payments of $0.2 million and $0.7 million, respectively.

As of March 31, 2021, we had gross unrecognized tax benefits of $5.9 million (exclusive of interest and federal and state benefits), all of which would reduce our effective tax rate if recognized.

Cash and Cash Equivalents and Restricted Cash and Cash Equivalents

At March 31, 2021, we had restricted cash and cash equivalents totaling $5.7 million, $2.7 million of which was held for future decommissioning of facilities (which is included in Other Assets on our condensed consolidated balance sheets) and $3.1 million of which was held to meet reinsurance reserve requirements of our captive insurer.

The following table provides a reconciliation of cash and cash equivalents and restricted cash and cash equivalents on our condensed consolidated balance sheets to the totals presented on our condensed consolidated statement of cash flows:


	March 31, 2021		December 31, 2020
	(In thousands)
Cash and cash equivalents	$	57,677	$	42,610
Restricted cash and cash equivalents	3,071		3,070
Restricted cash and cash equivalents included in Other Assets	2,672		2,618
Total cash and cash equivalents and restricted cash and cash equivalents as presented on our condensed consolidated statement of cash flows	$	63,420	$	48,298

Inventories

At March 31, 2021 and December 31, 2020, Other current assets included inventories totaling $13.9 million and $15.0 million, respectively, consisting entirely of raw materials and supplies.

Property, Plant and Equipment, Net

Property, plant and equipment, net is stated at cost and is set forth below:


	March 31, 2021		December 31, 2020
	(In thousands)
Land	$	9,591	$	9,585
Buildings	274,383		267,808
Machinery and equipment	849,960		827,785
Property under construction	451,274		420,374
	1,585,208		1,525,552
Less: Accumulated depreciation	701,208		709,081
Property, Plant and Equipment, Net	$	884,000	$	816,471

Accumulated Other Comprehensive Income (Loss)

The components of Accumulated other comprehensive income (loss) included in Stockholders' Equity are as follows:


	March 31, 2021		December 31, 2020
	(In thousands)
Currency translation adjustments	$	32,455	$	24,454
Net unrealized loss on derivative financial instruments	(1,074)		(496)
Unrecognized prior service cost on benefit obligations	(15,322)		(15,902)
Net unrealized gain on available-for-sale investments	231		142
Accumulated other comprehensive income (loss)	$	16,290	$	8,198

The amounts reclassified out of Accumulated other comprehensive income (loss) by component and the affected condensed consolidated statements of income line items are as follows:


	Three Months Ended March 31,
		2021		2020
Accumulated Other Comprehensive Income (Loss) Component Recognized		(In thousands)				Line Item Presented
Realized gain (loss) on derivative financial instruments		$	227	$	(1)	Revenues
		(5)		(557)		Cost of operations
		222		(558)		Total before tax
		(56)		138		Provision for Income Taxes
		$	166	$	(420)	Net Income
Amortization of prior service cost on benefit obligations		$	(737)	$	(777)	Other – net
		157		167		Provision for Income Taxes
		$	(580)	$	(610)	Net Income



Total reclassification for the period		$	(414)	$	(1,030)

Derivative Financial Instruments

Our operations give rise to exposure to market risks from changes in foreign currency exchange ("FX") rates. We use derivative financial instruments, primarily FX forward contracts, to reduce the impact of changes in FX rates on our operating results. We use these instruments to hedge our exposure associated with revenues or costs on our long-term contracts and other transactions that are denominated in currencies other than our operating entities' functional currencies. We do not hold or issue derivative financial instruments for trading or other speculative purposes.

We enter into derivative financial instruments primarily as hedges of certain firm purchase and sale commitments and loans between domestic and foreign subsidiaries denominated in foreign currencies. We record these contracts at fair value on our condensed consolidated balance sheets. Based on the hedge designation at the inception of the contract, the related gains and losses on these contracts are deferred in stockholders' equity as a component of Accumulated other comprehensive income until the hedged item is recognized in earnings. The gain or loss on a derivative instrument not designated as a hedging instrument is immediately recognized in earnings. Gains and losses on derivative financial instruments that require immediate recognition are included as a component of Other – net on our condensed consolidated statements of income.

We have designated the majority of our FX forward contracts that qualify for hedge accounting as cash flow hedges. The hedged risk is the risk of changes in functional-currency-equivalent cash flows attributable to changes in FX spot rates of forecasted transactions primarily related to long-term contracts. We exclude from our assessment of effectiveness the portion of the fair value of the FX forward contracts attributable to the difference between FX spot rates and FX forward rates. At March 31, 2021, we had deferred approximately $1.1 million of net losses on these derivative financial instruments. Assuming market conditions continue, we expect to recognize the majority of this amount in the next 12 months. For the three months ended March 31, 2021 and 2020, we recognized (gains) losses of $3.6 million and $(5.2) million, respectively, in Other – net on our condensed consolidated statements of income associated with FX forward contracts not designated as hedges.

At March 31, 2021, our derivative financial instruments consisted of FX forward contracts with a total notional value of $310.6 million with maturities extending to March 2023. These instruments consist primarily of FX forward contracts to purchase or sell Canadian dollars and Euros. We are exposed to credit-related losses in the event of non-performance by counterparties to derivative financial instruments. We attempt to mitigate this risk by using major financial institutions with high credit ratings. Our counterparties to derivative financial instruments have the benefit of the same collateral arrangements and covenants as described under our credit facility.

Acquisitions	3 Months Ended
Acquisitions	Mar. 31, 2021
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Laker Energy Products Ltd. On January 2, 2020, our subsidiary BWXT Canada Ltd. acquired Laker Energy Products Ltd., which was renamed BWXT Precision Manufacturing Inc. ("Precision Manufacturing"), for CAD 23.3 million ($17.8 million U.S. dollar equivalent). We are subject to the payment of contingent consideration totaling CAD 5.0 million, of which we have recognized CAD 2.5 million as a component of the purchase price. Our purchase price allocation resulted in the recognition of $8.4 million of Property, Plant and Equipment, Net, $8.2 million of Intangible Assets and $5.8 million of Goodwill. In addition, we recognized right-of-use assets and lease liabilities of $2.7 million. Precision Manufacturing is a global supplier of nuclear-grade materials and precisely machined components for CANDU nuclear power utilities, employs approximately 140 personnel and is reported as part of our Nuclear Power Group segment.

Revenue Recognition

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Revenue Recognition

REVENUE RECOGNITION

Disaggregated Revenues

Revenues by geographical area and customer type were as follows:


	Three Months Ended March 31, 2021								Three Months Ended March 31, 2020
	Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total		Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total
	(In thousands)
United States:
Government	$	379,243	$	—	$	22,769	$	402,012	$	401,066	$	—	$	24,596	$	425,662
Non-Government	20,666		10,272		1,668		32,606		20,841		9,608		11,209		41,658
	$	399,909	$	10,272	$	24,437	$	434,618	$	421,907	$	9,608	$	35,805	$	467,320
Canada:

Non-Government	$	—	$	91,355	$	1,020	$	92,375	$	—	$	74,527	$	960	$	75,487

Other:

Non-Government	$	2,159	$	5,771	$	26	$	7,956	$	1,868	$	3,782	$	—	$	5,650

Segment Revenues	$	402,068	$	107,398	$	25,483	534,949		$	423,775	$	87,917	$	36,765	548,457
Eliminations							(6,676)								(6,249)
Revenues							$	528,273							$	542,208

Revenues by timing of transfer of goods or services were as follows:


	Three Months Ended March 31, 2021								Three Months Ended March 31, 2020
	Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total		Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total
	(In thousands)
Over time	$	402,043	$	93,887	$	25,483	$	521,413	$	423,739	$	77,185	$	36,765	$	537,689
Point-in-time	25		13,511		—		13,536		36		10,732		—		10,768
Segment Revenues	$	402,068	$	107,398	$	25,483	534,949		$	423,775	$	87,917	$	36,765	548,457
Eliminations							(6,676)								(6,249)
Revenues							$	528,273							$	542,208

Revenues by contract type were as follows:


	Three Months Ended March 31, 2021								Three Months Ended March 31, 2020
	Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total		Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total
	(In thousands)
Fixed-Price Incentive Fee	$	302,325	$	490	$	—	$	302,815	$	284,374	$	492	$	—	$	284,866
Firm-Fixed-Price	75,369		68,057		5,540		148,966		113,337		70,836		11,637		195,810
Cost-Plus Fee	24,180		—		17,980		42,160		25,996		—		22,493		48,489
Time-and-Materials	194		38,851		1,963		41,008		68		16,589		2,635		19,292
Segment Revenues	$	402,068	$	107,398	$	25,483	534,949		$	423,775	$	87,917	$	36,765	548,457
Eliminations							(6,676)								(6,249)
Revenues							$	528,273							$	542,208

Performance Obligations

As we progress on our contracts and the underlying performance obligations for which we recognize revenue over time, we refine our estimates of variable consideration and total estimated costs at completion, which impact the overall profitability on our contracts and performance obligations. Changes in these estimates result in the recognition of cumulative catch-up adjustments that impact our revenues and/or costs of contracts. During the three months ended March 31, 2021 and 2020, we recognized net favorable changes in estimates that resulted in increases in revenues of $6.5 million and $9.6 million, respectively.

Contract Assets and Liabilities

We include revenues and related costs incurred, plus accumulated contract costs that exceed amounts invoiced to customers under the terms of the contracts, in Contracts in progress. We include in Advance billings on contracts billings that exceed accumulated contract costs and revenues recognized over time. Amounts that are withheld on our fixed-price incentive fee contracts are classified within Retainages. Certain of these amounts require conditions other than the passage of time to be achieved, with the remaining amounts only requiring the passage of time. Most long-term contracts contain provisions for progress payments. Our unbilled receivables do not contain an allowance for credit losses as we expect to invoice customers and collect all amounts for unbilled revenues. Changes in Contracts in progress and Advance billings on contracts are primarily driven by differences in the timing of revenue recognition and billings to our customers. During the three months ended March 31, 2021, our unbilled receivables increased $49.3 million primarily as a result of the timing of milestone billings on certain firm-fixed-price contracts within our Nuclear Power Group segment and increases in unbilled receivables on fixed-price incentive fee contracts within our Nuclear Operations Group segment. During the three months ended March 31, 2021, our Advance billings on contracts increased $15.6 million primarily as a result of billings in excess of revenue recognized within our Nuclear Operations Group segment. Our fixed-price incentive fee contracts for our Nuclear Operations Group segment include provisions that result in an increase in retainages on contracts during the first and third quarters of the year, with larger payments received during the second and fourth quarters. Retainages also vary as a result of timing differences between incurring costs and achieving milestones that allow us to recover these amounts.


	March 31,		December 31,
	2021		2020
	(In thousands)
Included in Contracts in progress:
Unbilled receivables	$	485,621	$	436,279
Retainages	$	81,820	$	55,172
Included in Other Assets:
Retainages	$	1,315	$	1,488
Advance billings on contracts	$	99,218	$	83,581

During the three months ended March 31, 2021 and 2020, we recognized $30.0 million and $30.2 million of revenues that were in Advance billings on contracts at December 31, 2020 and 2019, respectively.

Remaining Performance Obligations

Remaining performance obligations represent the dollar amount of revenue we expect to recognize in the future from performance obligations on contracts previously awarded and in progress. Of the remaining performance obligations on our contracts with customers at March 31, 2021, we expect to recognize revenues as follows:


	2021		2022		Thereafter		Total
	(In approximate millions)
Nuclear Operations Group	$	1,156	$	1,192	$	2,100	$	4,448
Nuclear Power Group	223		179		295		697
Nuclear Services Group	45		3		—		48
Total Remaining Performance Obligations	$	1,424	$	1,374	$	2,395	$	5,193

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
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-Paragraph 10
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Pension Plans and Postretirement Benefits

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Pension Plans and Postretirement Benefits

PENSION PLANS AND POSTRETIREMENT BENEFITSWe record the service cost component of net periodic benefit cost within Operating income on our condensed consolidated statements of income. For the three months ended March 31, 2021 and 2020, these amounts were $3.1 million and

$3.0 million, respectively. All other components of net periodic benefit cost are included in Other – net within the condensed consolidated statements of income. For the three months ended March 31, 2021 and 2020, these amounts were $(13.4) million and $(9.5) million, respectively. Components of net periodic benefit cost included in net income were as follows:


		Pension Benefits					Other Benefits
	Three Months Ended March 31,					Three Months Ended March 31,
		2021		2020			2021		2020
		(In thousands)
Service cost		$	2,957	$	2,819		$	190	$	166
Interest cost		6,754		9,302			282		410
Expected return on plan assets		(20,414)		(19,364)			(716)		(672)
Amortization of prior service cost (credit)		782		825			(45)		(48)

Net periodic benefit income		$	(9,921)	$	(6,418)		$	(289)	$	(144)

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
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+ Details

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIESThere were no material contingencies during the period covered by this Form 10-Q.

Fair Value Measurements

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

Investments

The following is a summary of our investments measured at fair value at March 31, 2021:


	Total		Level 1		Level 2		Level 3		Unclassified
	(In thousands)
Equity securities
Equities	$	800	$	—	$	—	$	800	$	—
Mutual funds	6,897		—		6,897		—		—
Available-for-sale securities
U.S. Government and agency securities	2,689		2,689		—		—		—
Corporate bonds	2,992		1,854		1,138		—		—
Asset-backed securities and collateralized mortgage obligations	61		—		61		—		—
Total	$	13,439	$	4,543	$	8,096	$	800	$	—

The following is a summary of our investments measured at fair value at December 31, 2020:


	Total		Level 1		Level 2		Level 3		Unclassified
	(In thousands)
Equity securities
Equities	$	800	$	—	$	—	$	800	$	—
Mutual funds	6,755		—		6,755		—		—
Available-for-sale securities
U.S. Government and agency securities	2,314		2,314		—		—		—
Corporate bonds	3,132		1,738		1,394		—		—
Asset-backed securities and collateralized mortgage obligations	62		—		62		—		—
Total	$	13,063	$	4,052	$	8,211	$	800	$	—

We estimate the fair value of investments based on quoted market prices. For investments for which there are no quoted market prices, we derive fair values from available yield curves for investments of similar quality and terms.

Derivatives

Level 2 derivative assets and liabilities currently consist of FX forward contracts. Where applicable, the value of these derivative assets and liabilities is computed by discounting the projected future cash flow amounts to present value using market-based observable inputs, including FX forward and spot rates, interest rates and counterparty performance risk adjustments. At March 31, 2021 and December 31, 2020, we had FX forward contracts outstanding to purchase or sell foreign currencies, primarily Canadian dollars and Euros, with a total fair value of $(1.7) million and $(2.2) million, respectively.

Other Financial Instruments

We used the following methods and assumptions in estimating our fair value disclosures for our other financial instruments, as follows:

Cash and cash equivalents and restricted cash and cash equivalents. The carrying amounts that we have reported in the accompanying condensed consolidated balance sheets for Cash and cash equivalents and Restricted cash and cash equivalents approximate their fair values due to their highly liquid nature.

Long-term and short-term debt. We base the fair values of debt instruments, including our 5.375% senior notes due 2026 (the "Senior Notes due 2026") and our 4.125% senior notes due 2028 (the "Senior Notes due 2028"), on quoted market prices. Where quoted prices are not available, we base the fair values on the present value of future cash flows discounted at estimated borrowing rates for similar debt instruments or on estimated prices based on current yields for debt issues of similar quality and terms. At March 31, 2021 and December 31, 2020, the fair value of our Senior Notes due 2026 was $413.8 million and $415.5 million, respectively. At March 31, 2021 and December 31, 2020, the fair value of our Senior Notes due 2028 was $405.0 million and $416.7 million, respectively. The fair value of our remaining debt instruments approximated their carrying values at March 31, 2021 and December 31, 2020.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Stock-Based Compensation	3 Months Ended
Stock-Based Compensation	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATIONStock-based compensation recognized for all of our plans for the three months ended March 31, 2021 and 2020 totaled $4.2 million and $2.6 million, respectively, with associated tax benefit totaling $0.7 million and $0.4 million, respectively.

Segment Reporting

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Segment Reporting

SEGMENT REPORTING

As described in Note 1, our operations are assessed based on three reportable segments. An analysis of our operations by reportable segment is as follows:


	Three Months Ended March 31,
		2021		2020
		(In thousands)
REVENUES:
Nuclear Operations Group		$	402,068	$	423,775
Nuclear Power Group		107,398		87,917
Nuclear Services Group		25,483		36,765
Eliminations (1)		(6,676)		(6,249)
		$	528,273	$	542,208

(1)Segment revenues are net of the following intersegment transfers:


Nuclear Operations Group Transfers	$	(940)	$	(673)
Nuclear Power Group Transfers	(181)		(129)
Nuclear Services Group Transfers	(5,555)		(5,447)
	$	(6,676)	$	(6,249)
OPERATING INCOME:
Nuclear Operations Group	$	74,360	$	90,359
Nuclear Power Group	10,318		8,470
Nuclear Services Group	5,747		6,400
Other	(5,886)		(5,359)
	$	84,539	$	99,870
Unallocated Corporate (2)	(2,125)		(1,603)
Total Operating Income	$	82,414	$	98,267
Other Income (Expense)	9,479		181
Income before Provision for Income Taxes	$	91,893	$	98,448

(2)Unallocated corporate includes general corporate overhead not allocated to segments.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details

Earnings Per Share

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Earnings Per Share

EARNINGS PER SHARE

The following table sets forth the computation of basic and diluted earnings per share:


	Three Months Ended March 31,
		2021		2020
		(In thousands, except share and per share amounts)
Basic:
Net Income Attributable to BWX Technologies, Inc.		$	69,749	$	75,499
Weighted-average common shares		95,303,728		95,412,351
Basic earnings per common share		$	0.73	$	0.79
Diluted:
Net Income Attributable to BWX Technologies, Inc.		$	69,749	$	75,499
Weighted-average common shares (basic)		95,303,728		95,412,351
Effect of dilutive securities:
Stock options, restricted stock units and performance shares (1)		255,135		344,021
Adjusted weighted-average common shares		95,558,863		95,756,372
Diluted earnings per common share		$	0.73	$	0.79

(1)At March 31, 2021 and 2020, we excluded 131,775 and 99,102 shares, respectively, from our diluted share calculation as their effect would have been antidilutive.

Subsequent Event	3 Months Ended
Subsequent Event	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Event	SUBSEQUENT EVENT On April 13, 2021, we issued $400 million aggregate principal amount of our 4.125% senior notes due 2029 (the "Senior Notes due 2029") pursuant to an indenture dated April 13, 2021 (the "2021 Indenture"), among the Company, certain of our subsidiaries, as guarantors, and U.S. Bank National Association, as trustee. Interest on the Senior Notes due 2029 will be payable semi-annually in cash in arrears on April 15 and October 15 of each year, commencing on October 15, 2021, at a rate of 4.125% per annum. The Senior Notes due 2029 will mature on April 15, 2029. The 2021 Indenture contains customary events of default, including, among other things, payment default, failure to comply with covenants or agreements contained in the 2021 Indenture or the Senior Notes due 2029 and certain provisions related to bankruptcy events. The 2021 Indenture also contains customary negative covenants. We intend to use the net proceeds from the issuance of the Senior Notes due 2029, together with cash on hand or borrowings under our credit facility, to redeem all of our outstanding Senior Notes due 2026 at the then-applicable redemption price. On and after July 15, 2021, we may redeem the Senior Notes due 2026, in whole or in part, at a redemption price equal to (i) 102.688% of the principal amount to be redeemed if the redemption occurs during the twelve-month period beginning on July 15, 2021, (ii) 101.344% of the principal amount to be redeemed if the redemption occurs during the twelve-month period beginning on July 15, 2022 and (iii) 100.0% of the principal amount to be redeemed if the redemption occurs on or after July 15, 2023, in each case plus accrued and unpaid interest, if any, to, but excluding, the redemption date. As of March 31, 2021, we have deferred financing costs of $4.5 million related to the Senior Notes due 2026.

Basis of Presentation and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	We have presented the condensed consolidated financial statements of BWX Technologies, Inc. ("BWXT" or the "Company") in U.S. dollars in accordance with the interim reporting requirements of Form 10-Q, Rule 10-01 of Regulation S-X and accounting principles generally accepted in the United States ("GAAP"). Certain financial information and disclosures normally included in our financial statements prepared annually in accordance with GAAP have been condensed or omitted. Readers of these financial statements should, therefore, refer to the consolidated financial statements and notes in our annual report on Form 10-K for the year ended December 31, 2020 (our "2020 10-K"). We have included all adjustments, in the opinion of management, consisting only of normal recurring adjustments, necessary for a fair presentation.
Consolidation	We use the equity method to account for investments in entities that we do not control, but over which we have the ability to exercise significant influence. We generally refer to these entities as "joint ventures." We have eliminated all intercompany transactions and accounts. We present the notes to our condensed consolidated financial statements on the basis of continuing operations, unless otherwise stated. Unless the context otherwise indicates, "we," "us" and "our" mean BWXT and its consolidated subsidiaries.
Reportable Segments	Reportable Segments We operate in three reportable segments: Nuclear Operations Group, Nuclear Power Group and Nuclear Services Group. Our reportable segments are further described as follows: •Our Nuclear Operations Group segment manufactures naval nuclear reactors for the U.S. Naval Nuclear Propulsion Program for use in submarines and aircraft carriers. Through this segment, we own and operate manufacturing facilities located in Lynchburg, Virginia; Barberton, Ohio; Mount Vernon, Indiana; Euclid, Ohio; and Erwin, Tennessee. The Lynchburg operations fabricate fuel-bearing precision components that range in weight from a few grams to hundreds of tons. In-house capabilities also include wet chemistry uranium processing, advanced heat treatment to optimize component material properties and a controlled, clean-room environment with the capacity to assemble railcar-size components. The Barberton and Mount Vernon locations specialize in the design and manufacture of heavy components inclusive of fabrication activities for submarine missile launch tubes. The Euclid facility fabricates electro-mechanical equipment and performs design, manufacturing, inspection, assembly and testing activities. Fuel for the naval nuclear reactors is provided by Nuclear Fuel Services, Inc. ("NFS"), one of our wholly owned subsidiaries. Located in Erwin, NFS also downblends Cold War-era government stockpiles of high-enriched uranium. •Our Nuclear Power Group segment fabricates commercial nuclear steam generators, nuclear fuel, fuel handling systems, pressure vessels, reactor components, heat exchangers, tooling delivery systems and other auxiliary equipment, including containers for the storage of spent nuclear fuel and other high-level waste and supplies nuclear-grade materials and precisely machined components for nuclear utility customers. BWXT has supplied the nuclear industry with more than 1,300 large, heavy components worldwide and is the only commercial heavy nuclear component manufacturer in North America. This segment also provides specialized engineering services that include structural component design, 3-D thermal-hydraulic engineering analysis, weld and robotic process development, electrical and controls engineering and metallurgy and materials engineering. In addition, this segment offers in-plant inspection, maintenance and modification services for nuclear steam generators, heat exchangers, reactors, fuel handling systems and balance of plant equipment, as well as specialized non-destructive examination and tooling/repair solutions. This segment is also a leading global manufacturer and supplier of critical medical radioisotopes and radiopharmaceuticals for research, diagnostic and therapeutic uses. •Our Nuclear Services Group segment provides various services to the U.S. Government including nuclear materials management and operation, environmental management and administrative and operating services for various U.S. Government-owned facilities. These services are provided to the U.S. Department of Energy ("DOE"), including the National Nuclear Security Administration ("NNSA"), the Office of Nuclear Energy, the Office of Science and the Office of Environmental Management, and NASA. Through this segment we deliver services and management solutions to nuclear and high-consequence operations. A significant portion of this segment's operations are conducted through joint ventures. This segment also develops technology for a variety of applications, including advanced nuclear power sources, and offers complete advanced nuclear fuel and reactor design and engineering, licensing and manufacturing services for new advanced nuclear reactors.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards There were no accounting standards adopted during the three months ended March 31, 2021.
Contracts and Revenue Recognition	Contracts and Revenue Recognition We generally recognize contract revenues and related costs over time for individual performance obligations based on a cost-to-cost method in accordance with FASB Topic Revenue from Contracts with Customers. We recognize estimated contract revenue and resulting income based on the measurement of the extent of progress toward completion as a percentage of the total project. Certain costs may be excluded from the cost-to-cost method of measuring progress, such as significant costs for uninstalled materials, if such costs do not depict our performance in transferring control of goods or services to the customer. We review contract price and cost estimates periodically as the work progresses and reflect adjustments proportionate to the percentage-of-completion in income in the period when those estimates are revised. Certain of our contracts recognize revenue at a point in time, and revenue on these contracts is recognized when control transfers to the customer. The majority of our revenue that is recognized at a point in time is related to parts and certain medical radioisotopes and radiopharmaceuticals in our Nuclear Power Group segment. For all contracts, if a current estimate of total contract cost indicates a loss on a contract, the projected loss is recognized in full when determined.
Provision for Income Taxes	Provision for Income Taxes We are subject to federal income tax in the U.S. and Canada as well as income tax within multiple U.S. state jurisdictions. We provide for income taxes based on the enacted tax laws and rates in the jurisdictions in which we conduct our operations. These jurisdictions may have regimes of taxation that vary with respect to nominal rates and with respect to the basis on which these rates are applied. This variation, along with the changes in our mix of income within these jurisdictions, can contribute to shifts in our effective tax rate from period to period.
Cash and Cash Equivalents and Restricted Cash and Cash Equivalents	Cash and Cash Equivalents and Restricted Cash and Cash Equivalents At March 31, 2021, we had restricted cash and cash equivalents totaling $5.7 million, $2.7 million of which was held for future decommissioning of facilities (which is included in Other Assets on our condensed consolidated balance sheets) and $3.1 million of which was held to meet reinsurance reserve requirements of our captive insurer.
Inventories	Inventories At March 31, 2021 and December 31, 2020, Other current assets included inventories totaling $13.9 million and $15.0 million, respectively, consisting entirely of raw materials and supplies.
Derivative Financial Instruments	Derivative Financial Instruments Our operations give rise to exposure to market risks from changes in foreign currency exchange ("FX") rates. We use derivative financial instruments, primarily FX forward contracts, to reduce the impact of changes in FX rates on our operating results. We use these instruments to hedge our exposure associated with revenues or costs on our long-term contracts and other transactions that are denominated in currencies other than our operating entities' functional currencies. We do not hold or issue derivative financial instruments for trading or other speculative purposes. We enter into derivative financial instruments primarily as hedges of certain firm purchase and sale commitments and loans between domestic and foreign subsidiaries denominated in foreign currencies. We record these contracts at fair value on our condensed consolidated balance sheets. Based on the hedge designation at the inception of the contract, the related gains and losses on these contracts are deferred in stockholders' equity as a component of Accumulated other comprehensive income until the hedged item is recognized in earnings. The gain or loss on a derivative instrument not designated as a hedging instrument is immediately recognized in earnings. Gains and losses on derivative financial instruments that require immediate recognition are included as a component of Other – net on our condensed consolidated statements of income. We have designated the majority of our FX forward contracts that qualify for hedge accounting as cash flow hedges. The hedged risk is the risk of changes in functional-currency-equivalent cash flows attributable to changes in FX spot rates of forecasted transactions primarily related to long-term contracts. We exclude from our assessment of effectiveness the portion of the fair value of the FX forward contracts attributable to the difference between FX spot rates and FX forward rates.

Basis of Presentation and Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2021

Accounting Policies [Abstract]

Restricted Cash and Cash Equivalents


	March 31, 2021		December 31, 2020
	(In thousands)
Cash and cash equivalents	$	57,677	$	42,610
Restricted cash and cash equivalents	3,071		3,070
Restricted cash and cash equivalents included in Other Assets	2,672		2,618
Total cash and cash equivalents and restricted cash and cash equivalents as presented on our condensed consolidated statement of cash flows	$	63,420	$	48,298

Restricted Cash and Cash Equivalents


	March 31, 2021		December 31, 2020
	(In thousands)
Cash and cash equivalents	$	57,677	$	42,610
Restricted cash and cash equivalents	3,071		3,070
Restricted cash and cash equivalents included in Other Assets	2,672		2,618
Total cash and cash equivalents and restricted cash and cash equivalents as presented on our condensed consolidated statement of cash flows	$	63,420	$	48,298

Property, Plant and Equipment, Net

Property, plant and equipment, net is stated at cost and is set forth below:


	March 31, 2021		December 31, 2020
	(In thousands)
Land	$	9,591	$	9,585
Buildings	274,383		267,808
Machinery and equipment	849,960		827,785
Property under construction	451,274		420,374
	1,585,208		1,525,552
Less: Accumulated depreciation	701,208		709,081
Property, Plant and Equipment, Net	$	884,000	$	816,471

Components of Accumulated Other Comprehensive Income (Loss)

Accumulated Other Comprehensive Income (Loss)

The components of Accumulated other comprehensive income (loss) included in Stockholders' Equity are as follows:


	March 31, 2021		December 31, 2020
	(In thousands)
Currency translation adjustments	$	32,455	$	24,454
Net unrealized loss on derivative financial instruments	(1,074)		(496)
Unrecognized prior service cost on benefit obligations	(15,322)		(15,902)
Net unrealized gain on available-for-sale investments	231		142
Accumulated other comprehensive income (loss)	$	16,290	$	8,198

Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)

The amounts reclassified out of Accumulated other comprehensive income (loss) by component and the affected condensed consolidated statements of income line items are as follows:


	Three Months Ended March 31,
		2021		2020
Accumulated Other Comprehensive Income (Loss) Component Recognized		(In thousands)				Line Item Presented
Realized gain (loss) on derivative financial instruments		$	227	$	(1)	Revenues
		(5)		(557)		Cost of operations
		222		(558)		Total before tax
		(56)		138		Provision for Income Taxes
		$	166	$	(420)	Net Income
Amortization of prior service cost on benefit obligations		$	(737)	$	(777)	Other – net
		157		167		Provision for Income Taxes
		$	(580)	$	(610)	Net Income



Total reclassification for the period		$	(414)	$	(1,030)

Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregated Revenues

Revenues by geographical area and customer type were as follows:


	Three Months Ended March 31, 2021								Three Months Ended March 31, 2020
	Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total		Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total
	(In thousands)
United States:
Government	$	379,243	$	—	$	22,769	$	402,012	$	401,066	$	—	$	24,596	$	425,662
Non-Government	20,666		10,272		1,668		32,606		20,841		9,608		11,209		41,658
	$	399,909	$	10,272	$	24,437	$	434,618	$	421,907	$	9,608	$	35,805	$	467,320
Canada:

Non-Government	$	—	$	91,355	$	1,020	$	92,375	$	—	$	74,527	$	960	$	75,487

Other:

Non-Government	$	2,159	$	5,771	$	26	$	7,956	$	1,868	$	3,782	$	—	$	5,650

Segment Revenues	$	402,068	$	107,398	$	25,483	534,949		$	423,775	$	87,917	$	36,765	548,457
Eliminations							(6,676)								(6,249)
Revenues							$	528,273							$	542,208

Revenues by timing of transfer of goods or services were as follows:


	Three Months Ended March 31, 2021								Three Months Ended March 31, 2020
	Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total		Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total
	(In thousands)
Over time	$	402,043	$	93,887	$	25,483	$	521,413	$	423,739	$	77,185	$	36,765	$	537,689
Point-in-time	25		13,511		—		13,536		36		10,732		—		10,768
Segment Revenues	$	402,068	$	107,398	$	25,483	534,949		$	423,775	$	87,917	$	36,765	548,457
Eliminations							(6,676)								(6,249)
Revenues							$	528,273							$	542,208

Revenues by contract type were as follows:


	Three Months Ended March 31, 2021								Three Months Ended March 31, 2020
	Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total		Nuclear Operations Group		Nuclear Power Group		Nuclear Services Group		Total
	(In thousands)
Fixed-Price Incentive Fee	$	302,325	$	490	$	—	$	302,815	$	284,374	$	492	$	—	$	284,866
Firm-Fixed-Price	75,369		68,057		5,540		148,966		113,337		70,836		11,637		195,810
Cost-Plus Fee	24,180		—		17,980		42,160		25,996		—		22,493		48,489
Time-and-Materials	194		38,851		1,963		41,008		68		16,589		2,635		19,292
Segment Revenues	$	402,068	$	107,398	$	25,483	534,949		$	423,775	$	87,917	$	36,765	548,457
Eliminations							(6,676)								(6,249)
Revenues							$	528,273							$	542,208

Schedule of Contract Assets and Liabilities


	March 31,		December 31,
	2021		2020
	(In thousands)
Included in Contracts in progress:
Unbilled receivables	$	485,621	$	436,279
Retainages	$	81,820	$	55,172
Included in Other Assets:
Retainages	$	1,315	$	1,488
Advance billings on contracts	$	99,218	$	83,581

Schedule of Remaining Performance Obligations

Of the remaining performance obligations on our contracts with customers at March 31, 2021, we expect to recognize revenues as follows:


	2021		2022		Thereafter		Total
	(In approximate millions)
Nuclear Operations Group	$	1,156	$	1,192	$	2,100	$	4,448
Nuclear Power Group	223		179		295		697
Nuclear Services Group	45		3		—		48
Total Remaining Performance Obligations	$	1,424	$	1,374	$	2,395	$	5,193

Pension Plans and Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Components of net periodic benefit cost included in net income were as follows:


		Pension Benefits					Other Benefits
	Three Months Ended March 31,					Three Months Ended March 31,
		2021		2020			2021		2020
		(In thousands)
Service cost		$	2,957	$	2,819		$	190	$	166
Interest cost		6,754		9,302			282		410
Expected return on plan assets		(20,414)		(19,364)			(716)		(672)
Amortization of prior service cost (credit)		782		825			(45)		(48)

Net periodic benefit income		$	(9,921)	$	(6,418)		$	(289)	$	(144)

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Summary of Investments Measured at Fair Value

The following is a summary of our investments measured at fair value at March 31, 2021:


	Total		Level 1		Level 2		Level 3		Unclassified
	(In thousands)
Equity securities
Equities	$	800	$	—	$	—	$	800	$	—
Mutual funds	6,897		—		6,897		—		—
Available-for-sale securities
U.S. Government and agency securities	2,689		2,689		—		—		—
Corporate bonds	2,992		1,854		1,138		—		—
Asset-backed securities and collateralized mortgage obligations	61		—		61		—		—
Total	$	13,439	$	4,543	$	8,096	$	800	$	—

The following is a summary of our investments measured at fair value at December 31, 2020:


	Total		Level 1		Level 2		Level 3		Unclassified
	(In thousands)
Equity securities
Equities	$	800	$	—	$	—	$	800	$	—
Mutual funds	6,755		—		6,755		—		—
Available-for-sale securities
U.S. Government and agency securities	2,314		2,314		—		—		—
Corporate bonds	3,132		1,738		1,394		—		—
Asset-backed securities and collateralized mortgage obligations	62		—		62		—		—
Total	$	13,063	$	4,052	$	8,211	$	800	$	—

Segment Reporting (Tables)

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Schedule of Operating Results by Segment

An analysis of our operations by reportable segment is as follows:


	Three Months Ended March 31,
		2021		2020
		(In thousands)
REVENUES:
Nuclear Operations Group		$	402,068	$	423,775
Nuclear Power Group		107,398		87,917
Nuclear Services Group		25,483		36,765
Eliminations (1)		(6,676)		(6,249)
		$	528,273	$	542,208

(1)Segment revenues are net of the following intersegment transfers:


Nuclear Operations Group Transfers	$	(940)	$	(673)
Nuclear Power Group Transfers	(181)		(129)
Nuclear Services Group Transfers	(5,555)		(5,447)
	$	(6,676)	$	(6,249)
OPERATING INCOME:
Nuclear Operations Group	$	74,360	$	90,359
Nuclear Power Group	10,318		8,470
Nuclear Services Group	5,747		6,400
Other	(5,886)		(5,359)
	$	84,539	$	99,870
Unallocated Corporate (2)	(2,125)		(1,603)
Total Operating Income	$	82,414	$	98,267
Other Income (Expense)	9,479		181
Income before Provision for Income Taxes	$	91,893	$	98,448

(2)Unallocated corporate includes general corporate overhead not allocated to segments.

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Computation of Basic and Diluted Earnings Per Share

The following table sets forth the computation of basic and diluted earnings per share:


	Three Months Ended March 31,
		2021		2020
		(In thousands, except share and per share amounts)
Basic:
Net Income Attributable to BWX Technologies, Inc.		$	69,749	$	75,499
Weighted-average common shares		95,303,728		95,412,351
Basic earnings per common share		$	0.73	$	0.79
Diluted:
Net Income Attributable to BWX Technologies, Inc.		$	69,749	$	75,499
Weighted-average common shares (basic)		95,303,728		95,412,351
Effect of dilutive securities:
Stock options, restricted stock units and performance shares (1)		255,135		344,021
Adjusted weighted-average common shares		95,558,863		95,756,372
Diluted earnings per common share		$	0.73	$	0.79

(1)At March 31, 2021 and 2020, we excluded 131,775 and 99,102 shares, respectively, from our diluted share calculation as their effect would have been antidilutive.

Basis of Presentation and Significant Accounting Policies - Additional Information (Details) $ in Millions		3 Months Ended
	May 29, 2020 USD ($)	Mar. 31, 2021 USD ($) segment component	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Noncash or Part Noncash Divestitures [Line Items]
Number of reportable segments \| segment		3
Number of components supplied to worldwide (more than) \| component		1,300
Effective tax rate		24.00%	23.20%
Benefits recognized for excess tax benefits related to employee share-based payments		$ 0.2	$ 0.7
Unrecognized tax benefits that would impact effective tax rate		5.9
Restricted cash and cash equivalents		5.7
Total inventories		13.9		$ 15.0
Net gains on foreign exchange forward contracts		1.1
Recognized gain on FX forward contracts not designated as hedges		3.6	$ (5.2)
Notional amount of foreign currency forward contracts		310.6
Cash Held for Decommissioning of Facilities
Noncash or Part Noncash Divestitures [Line Items]
Restricted cash and cash equivalents		2.7
Cash Held to Meet Reinsurance Reserve Requirements
Noncash or Part Noncash Divestitures [Line Items]
Restricted cash and cash equivalents		$ 3.1
Nuclear Services Business
Noncash or Part Noncash Divestitures [Line Items]
Net assets exchanged in non-cash transaction	$ 18.0

Basis of Presentation and Significant Accounting Policies - Reconciliation of Cash and Cash Equivalents and Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Basis Of Presentation And Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 57,677	$ 42,610
Restricted cash and cash equivalents	3,071	3,070
Restricted cash and cash equivalents included in Other Assets	2,672	2,618
Total cash and cash equivalents and restricted cash and cash equivalents as presented on our condensed consolidated statement of cash flows	$ 63,420	$ 48,298	$ 83,542	$ 92,400

Basis of Presentation and Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,585,208	$ 1,525,552
Less: Accumulated depreciation	701,208	709,081
Property, Plant and Equipment, Net	884,000	816,471
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment	9,591	9,585
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment	274,383	267,808
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	849,960	827,785
Property under construction
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 451,274	$ 420,374

Basis of Presentation and Significant Accounting Policies - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	$ 656,306	$ 617,768	$ 429,512	$ 404,112
Currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	32,455	24,454
Net unrealized loss on derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	(1,074)	(496)
Unrecognized prior service cost on benefit obligations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	(15,322)	(15,902)
Net unrealized gain (loss) on available-for-sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	231	142
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	$ 16,290	$ 8,198	$ (18,645)	$ (7,448)

- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=115929471&loc=d3e21930-107793

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32136-110900

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 45
-Paragraph 23
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=115929471&loc=d3e21914-107793

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 4
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (f)(2)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 16
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Basis of Presentation and Significant Accounting Policies - Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues	$ 528,273	$ 542,208
Cost of operations	(392,806)	(392,443)
Income before Provision for Income Taxes	91,893	98,448
Provision for Income Taxes	(22,078)	(22,828)
Other – net	16,386	7,917
Net Income	69,815	75,620
Accumulated Other Comprehensive Income (Loss) Component Recognized
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income	(414)	(1,030)
Accumulated Other Comprehensive Income (Loss) Component Recognized \| Realized gain (loss) on derivative financial instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues	227	(1)
Cost of operations	(5)	(557)
Income before Provision for Income Taxes	222	(558)
Provision for Income Taxes	(56)	138
Net Income	166	(420)
Accumulated Other Comprehensive Income (Loss) Component Recognized \| Amortization of prior service cost on benefit obligations
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	157	167
Other – net	(737)	(777)
Net Income	$ (580)	$ (610)

Acquisitions - Additional Information (Detail) $ in Thousands, $ in Millions	Jan. 02, 2020 USD ($) personnel	Jan. 02, 2020 CAD ($) personnel	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jan. 02, 2020 CAD ($)
Business Acquisition [Line Items]
Goodwill			$ 285,992	$ 283,708
Laker Energy Products, Ltd
Business Acquisition [Line Items]
Purchase of business	$ 17,800	$ 23.3
Contingent consideration					$ 5.0
Property, plant and equipment	8,400
Intangible assets	8,200
Goodwill	5,800
Right-of-use assets	2,700
Lease liabilities	$ 2,700
Number of personnel acquired \| personnel	140	140

Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 528,273	$ 542,208
Fixed-Price Incentive Fee
Disaggregation of Revenue [Line Items]
Revenues	302,815	284,866
Firm-Fixed-Price
Disaggregation of Revenue [Line Items]
Revenues	148,966	195,810
Cost-Plus Fee
Disaggregation of Revenue [Line Items]
Revenues	42,160	48,489
Time-and-Materials
Disaggregation of Revenue [Line Items]
Revenues	41,008	19,292
Over time
Disaggregation of Revenue [Line Items]
Revenues	521,413	537,689
Point-in-time
Disaggregation of Revenue [Line Items]
Revenues	13,536	10,768
United States:
Disaggregation of Revenue [Line Items]
Revenues	434,618	467,320
United States: \| Government
Disaggregation of Revenue [Line Items]
Revenues	402,012	425,662
United States: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	32,606	41,658
Canada: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	92,375	75,487
Other: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	7,956	5,650
Nuclear Operations Group
Disaggregation of Revenue [Line Items]
Revenues	402,068	423,775
Nuclear Operations Group \| Fixed-Price Incentive Fee
Disaggregation of Revenue [Line Items]
Revenues	302,325	284,374
Nuclear Operations Group \| Firm-Fixed-Price
Disaggregation of Revenue [Line Items]
Revenues	75,369	113,337
Nuclear Operations Group \| Cost-Plus Fee
Disaggregation of Revenue [Line Items]
Revenues	24,180	25,996
Nuclear Operations Group \| Time-and-Materials
Disaggregation of Revenue [Line Items]
Revenues	194	68
Nuclear Operations Group \| Over time
Disaggregation of Revenue [Line Items]
Revenues	402,043	423,739
Nuclear Operations Group \| Point-in-time
Disaggregation of Revenue [Line Items]
Revenues	25	36
Nuclear Power Group
Disaggregation of Revenue [Line Items]
Revenues	107,398	87,917
Nuclear Power Group \| Fixed-Price Incentive Fee
Disaggregation of Revenue [Line Items]
Revenues	490	492
Nuclear Power Group \| Firm-Fixed-Price
Disaggregation of Revenue [Line Items]
Revenues	68,057	70,836
Nuclear Power Group \| Cost-Plus Fee
Disaggregation of Revenue [Line Items]
Revenues	0	0
Nuclear Power Group \| Time-and-Materials
Disaggregation of Revenue [Line Items]
Revenues	38,851	16,589
Nuclear Power Group \| Over time
Disaggregation of Revenue [Line Items]
Revenues	93,887	77,185
Nuclear Power Group \| Point-in-time
Disaggregation of Revenue [Line Items]
Revenues	13,511	10,732
Nuclear Services Group
Disaggregation of Revenue [Line Items]
Revenues	25,483	36,765
Nuclear Services Group \| Fixed-Price Incentive Fee
Disaggregation of Revenue [Line Items]
Revenues	0	0
Nuclear Services Group \| Firm-Fixed-Price
Disaggregation of Revenue [Line Items]
Revenues	5,540	11,637
Nuclear Services Group \| Cost-Plus Fee
Disaggregation of Revenue [Line Items]
Revenues	17,980	22,493
Nuclear Services Group \| Time-and-Materials
Disaggregation of Revenue [Line Items]
Revenues	1,963	2,635
Nuclear Services Group \| Over time
Disaggregation of Revenue [Line Items]
Revenues	25,483	36,765
Nuclear Services Group \| Point-in-time
Disaggregation of Revenue [Line Items]
Revenues	0	0
Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	534,949	548,457
Operating Segments \| Nuclear Operations Group
Disaggregation of Revenue [Line Items]
Revenues	402,068	423,775
Operating Segments \| Nuclear Operations Group \| United States:
Disaggregation of Revenue [Line Items]
Revenues	399,909	421,907
Operating Segments \| Nuclear Operations Group \| United States: \| Government
Disaggregation of Revenue [Line Items]
Revenues	379,243	401,066
Operating Segments \| Nuclear Operations Group \| United States: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	20,666	20,841
Operating Segments \| Nuclear Operations Group \| Canada: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	0	0
Operating Segments \| Nuclear Operations Group \| Other: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	2,159	1,868
Operating Segments \| Nuclear Power Group
Disaggregation of Revenue [Line Items]
Revenues	107,398	87,917
Operating Segments \| Nuclear Power Group \| United States:
Disaggregation of Revenue [Line Items]
Revenues	10,272	9,608
Operating Segments \| Nuclear Power Group \| United States: \| Government
Disaggregation of Revenue [Line Items]
Revenues	0	0
Operating Segments \| Nuclear Power Group \| United States: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	10,272	9,608
Operating Segments \| Nuclear Power Group \| Canada: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	91,355	74,527
Operating Segments \| Nuclear Power Group \| Other: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	5,771	3,782
Operating Segments \| Nuclear Services Group
Disaggregation of Revenue [Line Items]
Revenues	25,483	36,765
Operating Segments \| Nuclear Services Group \| United States:
Disaggregation of Revenue [Line Items]
Revenues	24,437	35,805
Operating Segments \| Nuclear Services Group \| United States: \| Government
Disaggregation of Revenue [Line Items]
Revenues	22,769	24,596
Operating Segments \| Nuclear Services Group \| United States: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	1,668	11,209
Operating Segments \| Nuclear Services Group \| Canada: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	1,020	960
Operating Segments \| Nuclear Services Group \| Other: \| Non-Government
Disaggregation of Revenue [Line Items]
Revenues	26	0
Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(6,676)	(6,249)
Eliminations \| Nuclear Operations Group
Disaggregation of Revenue [Line Items]
Revenues	$ (940)	$ (673)

Revenue Recognition - Additional Details (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Net favorable changes in estimate that resulted in an increase in revenue	$ 6.5	$ 9.6
Contracts in progress increase	49.3
Change in advanced billings	15.6
Revenue recognized from advance billings on contracts	$ 30.0	$ 30.2

Revenue Recognition - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Contracts with Customers, Asset and Liability [Line Items]
Advance billings on contracts	$ 99,218	$ 83,581
Unbilled receivables
Contracts with Customers, Asset and Liability [Line Items]
Contract with customer, asset	485,621	436,279
Retainages
Contracts with Customers, Asset and Liability [Line Items]
Contract with customer, asset	81,820	55,172
Retainages
Contracts with Customers, Asset and Liability [Line Items]
Contract with customer, asset	$ 1,315	$ 1,488

Revenue Recognition - Remaining Performance Obligations Total (Details) $ in Millions	Mar. 31, 2021 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total Remaining Performance Obligations	$ 5,193
Nuclear Operations Group
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total Remaining Performance Obligations	4,448
Nuclear Power Group
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total Remaining Performance Obligations	697
Nuclear Services Group
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total Remaining Performance Obligations	$ 48

Pension Plans and Postretirement Benefits - Additional Details (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Retirement Benefits [Abstract]
Service cost	$ 3.1	$ 3.0
Net periodic benefit (income) cost, excluding service costs	$ (13.4)	$ (9.5)

Pension Plans and Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,100	$ 3,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,957	2,819
Interest cost	6,754	9,302
Expected return on plan assets	(20,414)	(19,364)
Amortization of prior service cost (credit)	782	825
Net periodic benefit income	(9,921)	(6,418)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	190	166
Interest cost	282	410
Expected return on plan assets	(716)	(672)
Amortization of prior service cost (credit)	(45)	(48)
Net periodic benefit income	$ (289)	$ (144)

Fair Value Measurements - Summary of Investments and Available-for-Sale Securities Measured at Fair Value (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	$ 13,439	$ 13,063
Equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	800	800
Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	6,897	6,755
U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,689	2,314
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,992	3,132
Asset-backed securities and collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	61	62
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	4,543	4,052
Level 1 \| Equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Level 1 \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Level 1 \| U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,689	2,314
Level 1 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,854	1,738
Level 1 \| Asset-backed securities and collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	8,096	8,211
Level 2 \| Equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Level 2 \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	6,897	6,755
Level 2 \| U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,138	1,394
Level 2 \| Asset-backed securities and collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	61	62
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	800	800
Level 3 \| Equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	800	800
Level 3 \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Level 3 \| U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Level 3 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Level 3 \| Asset-backed securities and collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 0	$ 0

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Senior Notes \| Senior Notes Due 2026
Fair Values Of Financial Instruments [Line Items]
Stated interest rate on senior notes	5.375%
Fair value of senior notes	$ 413.8	$ 415.5
Senior Notes \| Senior Notes Due 2028
Fair Values Of Financial Instruments [Line Items]
Stated interest rate on senior notes	4.125%
Fair value of senior notes	$ 405.0	416.7
FX Forward Contracts
Fair Values Of Financial Instruments [Line Items]
Fair value of foreign currency forward contracts	$ (1.7)	$ (2.2)

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock based compensation expense	$ 4.2	$ 2.6
Stock-based compensation, tax benefits	$ 0.7	$ 0.4

Segment Reporting - Additional Information (Details)	3 Months Ended
Segment Reporting - Additional Information (Details)	Mar. 31, 2021 segment
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Number of reportable segments	3

Segment Reporting - Schedule of Operating Results by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	$ 528,273	$ 542,208
OPERATING INCOME:
Total Operating Income	82,414	98,267
Other Income (Expense)	9,479	181
Income before Provision for Income Taxes	91,893	98,448
Nuclear Operations Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	402,068	423,775
Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	534,949	548,457
OPERATING INCOME:
Total Operating Income	84,539	99,870
Operating Segments \| Nuclear Operations Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	402,068	423,775
OPERATING INCOME:
Total Operating Income	74,360	90,359
Operating Segments \| Nuclear Power Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	107,398	87,917
OPERATING INCOME:
Total Operating Income	10,318	8,470
Operating Segments \| Nuclear Services Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	25,483	36,765
OPERATING INCOME:
Total Operating Income	5,747	6,400
Eliminations
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	(6,676)	(6,249)
Eliminations \| Nuclear Operations Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	(940)	(673)
Eliminations \| Nuclear Power Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	(181)	(129)
Eliminations \| Nuclear Services Group
Segment Reporting, Other Significant Reconciling Item [Line Items]
Revenues	(5,555)	(5,447)
Segment Reconciling Items
OPERATING INCOME:
Total Operating Income	(5,886)	(5,359)
Unallocated Corporate
OPERATING INCOME:
Total Operating Income	$ (2,125)	$ (1,603)

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic:
Net Income Attributable to BWX Technologies, Inc.	$ 69,749	$ 75,499
Weighted-average common shares (in shares)	95,303,728	95,412,351
Basic earnings per common share (in usd per share)	$ 0.73	$ 0.79
Diluted:
Net Income Attributable to BWX Technologies, Inc.	$ 69,749	$ 75,499
Weighted-average common shares (in shares)	95,303,728	95,412,351
Effect of dilutive securities:
Stock options, restricted stock units and performance shares (in shares)	255,135	344,021
Adjusted weighted-average common shares (in shares)	95,558,863	95,756,372
Diluted earnings per common share (in usd per share)	$ 0.73	$ 0.79
Number of shares that would be antidilutive (in shares)	131,775	99,102

Subsequent Events (Details) - Senior Notes - USD ($)	3 Months Ended
Subsequent Events (Details) - Senior Notes - USD ($)	Mar. 31, 2021	Apr. 13, 2021
Subsequent Event [Line Items]
Deferred debt issuance costs	$ 4,500,000
Senior Notes Due 2029 \| Subsequent Event
Subsequent Event [Line Items]
Aggregate principal amount of debt issued		$ 400,000,000
Stated interest rate		4.125%
Senior Notes Due 2026
Subsequent Event [Line Items]
Stated interest rate	5.375%
Senior Notes Due 2026 \| On and after July 15, 2021
Subsequent Event [Line Items]
Redemption price as a percentage	102.688%
Senior Notes Due 2026 \| On and after July 15, 2022
Subsequent Event [Line Items]
Redemption price as a percentage	101.344%
Senior Notes Due 2026 \| On and after July 15, 2023
Subsequent Event [Line Items]
Redemption price as a percentage	100.00%