Significant Accounting Principles and Policies - Impact of Restatement on Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 28, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 118,150	$ 85,908
Accounts receivable, net	562,398	585,511
Prepaid expenses and other current assets	69,902	61,607
Total current assets	750,450	733,026
Property and equipment, net	27,652	27,615
Deferred income taxes, net		0
Investments	19,400	18,272
Goodwill	591,209	590,668
Intangible assets, net	245,995	258,210
Operating lease right-of-use assets, net	183,276	191,370
Other noncurrent assets	10,283	10,209
Total assets	1,828,265	1,829,370
Current liabilities:
Accounts payable	177,911	152,962
Accrued expenses	121,274	114,222
Customer advances and billings in excess of costs	74,197	106,475
Salaries, benefits and payroll taxes	158,841	145,186
Accrued taxes	15,186	15,582
Current portion of long-term debt, net	5,920	5,961
Operating lease liabilities, current portion	47,163	46,756
Other current liabilities	42,393	45,037
Total current liabilities	642,885	632,181
Deferred income taxes, net	6,587	4,389
Long-term debt, net	861,057	860,306
Long-term operating lease liabilities	136,473	145,569
Warrant liability	49,267	50,467
Other long-term liabilities	32,441	30,273
Total liabilities	1,728,710	1,723,185
Stockholders’ equity:
Preferred stock, $0.0001 par value per share, 1,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.0001 par value per share: 210,000,000 shares authorized; 93,069,815 and 92,040,654 shares issued and outstanding as of March 28, 2021 and December 31, 2020, respectively	9	9
Additional paid-in capital	167,898	188,685
Accumulated deficit	(103,237)	(116,621)
Accumulated other comprehensive income	881	1,876
Total PAE Incorporated stockholders' equity	65,551	73,949
Noncontrolling interests	34,004	32,236
Total liabilities and stockholders’ equity	$ 1,828,265	1,829,370
As filed
Current assets:
Cash and cash equivalents		85,908
Accounts receivable, net		585,511
Prepaid expenses and other current assets		61,607
Total current assets		733,026
Property and equipment, net		27,615
Deferred income taxes, net		0
Investments		18,272
Goodwill		590,668
Intangible assets, net		258,210
Operating lease right-of-use assets, net		191,370
Other noncurrent assets		10,209
Total assets		1,829,370
Current liabilities:
Accounts payable		152,962
Accrued expenses		114,222
Customer advances and billings in excess of costs		106,475
Salaries, benefits and payroll taxes		145,186
Accrued taxes		15,582
Current portion of long-term debt, net		5,961
Operating lease liabilities, current portion		46,756
Other current liabilities		45,037
Total current liabilities		632,181
Deferred income taxes, net		4,389
Long-term debt, net		860,306
Long-term operating lease liabilities		145,569
Warrant liability		0
Other long-term liabilities		30,273
Total liabilities		1,672,718
Stockholders’ equity:
Preferred stock, $0.0001 par value per share, 1,000,000 shares authorized; no shares issued and outstanding		0
Common stock, $0.0001 par value per share: 210,000,000 shares authorized; 93,069,815 and 92,040,654 shares issued and outstanding as of March 28, 2021 and December 31, 2020, respectively		9
Additional paid-in capital		252,612
Accumulated deficit		(130,081)
Accumulated other comprehensive income		1,876
Total PAE Incorporated stockholders' equity		124,416
Noncontrolling interests		32,236
Total liabilities and stockholders’ equity		1,829,370
Restatement adjustments
Current assets:
Cash and cash equivalents		0
Accounts receivable, net		0
Prepaid expenses and other current assets		0
Total current assets		0
Property and equipment, net		0
Deferred income taxes, net		0
Investments		0
Goodwill		0
Intangible assets, net		0
Operating lease right-of-use assets, net		0
Other noncurrent assets		0
Total assets		0
Current liabilities:
Accounts payable		0
Accrued expenses		0
Customer advances and billings in excess of costs		0
Salaries, benefits and payroll taxes		0
Accrued taxes		0
Current portion of long-term debt, net		0
Operating lease liabilities, current portion		0
Other current liabilities		0
Total current liabilities		0
Deferred income taxes, net		0
Long-term debt, net		0
Long-term operating lease liabilities		0
Warrant liability		50,467
Other long-term liabilities		0
Total liabilities		50,467
Stockholders’ equity:
Preferred stock, $0.0001 par value per share, 1,000,000 shares authorized; no shares issued and outstanding		0
Common stock, $0.0001 par value per share: 210,000,000 shares authorized; 93,069,815 and 92,040,654 shares issued and outstanding as of March 28, 2021 and December 31, 2020, respectively		0
Additional paid-in capital		(63,927)
Accumulated deficit		13,460
Accumulated other comprehensive income		0
Total PAE Incorporated stockholders' equity		(50,467)
Noncontrolling interests		0
Total liabilities and stockholders’ equity		$ 0