Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net Income	$ 64,396	$ 59,000	$ 140,016	$ 108,110
Other Comprehensive Income (Loss):
Currency translation adjustments	856	4,295	(11,084)	5,238
Derivative financial instruments:
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	(404)	(634)	(91)	(1,075)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	(89)	203	331	62
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax	609	493	1,219	1,004
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	154	27	(446)	51
Other Comprehensive Income (Loss)	1,126	4,384	(10,071)	5,280
Total Comprehensive Income	65,522	63,384	129,945	113,390
Comprehensive Income Attributable to Noncontrolling Interest	(138)	(122)	(259)	(254)
Comprehensive Income Attributable to BWX Technologies, Inc.	$ 65,384	$ 63,262	$ 129,686	$ 113,136