Net Income (Loss) Per Share - Computation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Numerator:
Net income (loss) attributed to PAE Incorporated	$ 10,318	$ (32,170)	$ 21,395	$ (35,216)
Denominator:
Basic weighted average shares (in shares)	92,070,306	21,127,823	81,323,258	21,127,823
Diluted weighted average shares (in shares)	93,392,565	21,127,823	82,115,825	21,127,823
Basic income (loss) per share (in dollars per share)	$ 0.11	$ (1.52)	$ 0.26	$ (1.67)
Diluted income (loss) per share (in dollars per share)	$ 0.11	$ (1.52)	$ 0.26	$ (1.67)