Significant Accounting Principles and Policies - Impact of Restatement on Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 28, 2021	Mar. 29, 2020
Reclassification [Line Items]
Revenues	$ 748,567	$ 617,253
Cost of revenues	566,666	465,208
Selling, general and administrative expenses	145,291	137,326
Amortization of intangible assets	12,215	8,047
Total operating expenses	724,172	610,581
Program profit	24,395	6,672
Other loss, net	1,801	785
Operating income	26,196	7,457
Interest expense, net	(12,514)	(20,948)
Other income, net	1,200	30,112
Income before income taxes	14,882	16,621
Expense (benefit) from income taxes	2,609	(9,529)
Net income	12,273	26,150
Noncontrolling interest in earnings of ventures	(1,111)	166
Net income (loss)	$ 13,384	$ 25,984
Net income per share attributed to PAE Incorporated:
Basic income per share (in dollars per share)	$ 0.14	$ 0.43
Diluted income per share (in dollars per share)	$ 0.14	$ 0.43
Weighted average shares outstanding:
Basic weighted average shares (in shares)	92,613,057	59,807,549
Diluted weighted average shares (in shares)	95,128,326	59,807,549
As filed
Reclassification [Line Items]
Revenues		$ 617,253
Cost of revenues		465,208
Selling, general and administrative expenses		137,326
Amortization of intangible assets		8,047
Total operating expenses		610,581
Program profit		6,672
Other loss, net		785
Operating income		7,457
Interest expense, net		(20,948)
Other income, net		0
Income before income taxes		(13,491)
Expense (benefit) from income taxes		(8,714)
Net income		(4,777)
Noncontrolling interest in earnings of ventures		166
Net income (loss)		$ (4,943)
Net income per share attributed to PAE Incorporated:
Basic income per share (in dollars per share)		$ (0.08)
Diluted income per share (in dollars per share)		$ (0.08)
Weighted average shares outstanding:
Basic weighted average shares (in shares)		59,807,549
Diluted weighted average shares (in shares)		59,807,549
Restatement adjustments
Reclassification [Line Items]
Revenues		$ 0
Cost of revenues		0
Selling, general and administrative expenses		0
Amortization of intangible assets		0
Total operating expenses		0
Program profit		0
Other loss, net		0
Operating income		0
Interest expense, net		0
Other income, net		30,112
Income before income taxes		30,112
Expense (benefit) from income taxes		(815)
Net income		30,927
Noncontrolling interest in earnings of ventures		0
Net income (loss)		$ 30,927
Net income per share attributed to PAE Incorporated:
Basic income per share (in dollars per share)		$ 0.51
Diluted income per share (in dollars per share)		$ 0.51
Weighted average shares outstanding:
Basic weighted average shares (in shares)		59,807,549
Diluted weighted average shares (in shares)		59,807,549