XML 81 R67.htm IDEA: XBRL DOCUMENT
v3.20.4

Equity Method Investments - Schedule of Transactions with Unconsolidated Affiliates (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract] |  |  |
Sales to | $ 12,186 | $ 14,668 | $ 18,454
Dividends received | 25,005 | 20,955 | 22,237
Capital contributions, net of returns | $ (88) | $ (255) | $ 9,059

X
- Definition Payments To (Proceeds) From Equity Method Investments, Net Of Return Of Capital + References No definition available. + Details
Name: | bwxt_PaymentsToProceedsFromEquityMethodInvestmentsNetOfReturnOfCapital
Namespace Prefix: | bwxt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(12)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 21D -URI http://asc.fasb.org/extlink&oid=121586364&loc=SL94080555-108585 + Details
Name: | us-gaap_EquityMethodInvestmentDividendsOrDistributions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_EquityMethodInvestmentsAndJointVenturesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration