Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended							6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Dec. 31, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 28, 2020	Sep. 27, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 15,731	$ (2,681)	$ 26,150	$ (16,664)	$ (31,625)	$ 3,388	$ (5,160)	$ 23,469	$ 39,199	$ 27,286	$ (50,061)	$ (31,578)
Other comprehensive income (loss):
Change in foreign currency translation adjustment, net of tax	780	59	(976)					(917)	(137)	1,583	317	(1,061)
Other, net	1	142	281					424	424	427	1,687	1,686
Other comprehensive income	781	201	(695)					(493)	287	2,010	2,004	625
Comprehensive income (loss)	16,512	(2,480)	25,455					22,976	39,486	29,296	(48,057)	(30,953)
Comprehensive (loss) income attributed to noncontrolling interests	505	284	498					781	1,287	(1,084)	(178)	2,656
Comprehensive income (loss) attributed to PAE Incorporated	$ 16,007	$ (2,764)	$ 24,957					$ 22,195	$ 38,199	$ 30,380	$ (47,879)	$ (33,609)