Net Income (loss) Per Share - Computation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2021	Jun. 28, 2020	Jun. 27, 2021	Jun. 28, 2020
Numerator:
Net income (loss) attributed to PAE Incorporated	$ 14,350	$ (3,446)	$ 27,734	$ 22,538
Denominator:
Basic weighted average shares (in shares)	93,097,652	92,044,098	92,860,800	75,890,028
Diluted weighted average shares (in shares)	95,511,269	92,787,379	95,193,549	76,273,931
Basic income (loss) per share (in dollars per share)	$ 0.15	$ (0.04)	$ 0.30	$ 0.30
Diluted income (loss) per share (in dollars per share)	$ 0.15	$ (0.04)	$ 0.29	$ 0.30