Net Income Per Share - Computation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 28, 2021	Mar. 29, 2020
Numerator:
Net income attributed to PAE Incorporated	$ 13,384	$ 25,984
Denominator:
Basic weighted average shares (in shares)	92,613,057	59,807,549
Diluted weighted average shares (in shares)	95,128,326	59,807,549
Basic income per share (in dollars per share)	$ 0.14	$ 0.43
Diluted income per share (in dollars per share)	$ 0.14	$ 0.43