Restatement of Previously Issued Audited and Unaudited Consolidated Financial Statements - Impact of Restatement on Statements of Comprehensive Income (Details) - 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
Reclassification [Line Items]
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)
Previously Reported
Reclassification [Line Items]
Net income (loss)	10,731	16,786	(4,777)					12,009	22,739	13,826
Other comprehensive income (loss):
Change in foreign currency translation adjustment, net of tax	780	59	(976)					(917)	(137)	1,583
Other, net	1	142	281					424	424	427
Other comprehensive income	781	201	(695)					(493)	287	2,010
Comprehensive income (loss)	11,512	16,987	(5,472)					11,516	23,026	15,836
Comprehensive (loss) income attributed to noncontrolling interests	505	284	498					781	1,287	(1,084)
Comprehensive income (loss) attributed to PAE Incorporated	11,007	16,703	(5,970)					10,735	21,739	16,920
Restatement Adjustment
Reclassification [Line Items]
Net income (loss)	5,000	(19,467)	30,927					11,460	16,460	13,460
Other comprehensive income (loss):
Change in foreign currency translation adjustment, net of tax	0	0	0					0	0	0
Other, net	0	0	0					0	0	0
Other comprehensive income	0	0	0					0	0	0
Comprehensive income (loss)	5,000	(19,467)	30,927					11,460	16,460	13,460
Comprehensive (loss) income attributed to noncontrolling interests	0	0	0					0	0	0
Comprehensive income (loss) attributed to PAE Incorporated	$ 5,000	$ (19,467)	$ 30,927					$ 11,460	$ 16,460	$ 13,460