Restatement of Previously Issued Audited and Unaudited Consolidated Financial Statements - Impact of Restatement on Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 85,908	$ 145,446	$ 138,469	$ 99,790	$ 68,035
Accounts receivable, net	585,511	445,429	432,185	420,765	442,180
Prepaid expenses and other current assets	61,607	44,363	45,676	46,760	43,549
Total current assets	733,026	635,238	616,330	567,315	553,764
Property and equipment, net	27,615	25,696	26,841	28,079	30,404
Deferred income taxes, net	0	13,419	12,017	16,597	3,212
Investments	18,272	18,961	17,848	17,747	17,925
Goodwill	590,668	409,588	409,588	409,588	409,588	$ 408,025
Intangible assets, net	258,210	156,323	164,370	172,417	180,464
Operating lease right-of-use assets, net	191,370	159,975	154,375	161,731	162,184
Other noncurrent assets	10,209	9,762	9,663	9,484	13,758
Total assets	1,829,370	1,428,962	1,411,032	1,382,958	1,371,299
Current liabilities:
Accounts payable	152,962	140,515	107,154	122,126	124,661
Accrued expenses	114,222	103,025	128,992	100,456	102,315
Customer advances and billings in excess of costs	106,475	60,390	70,695	69,662	51,439
Salaries, benefits and payroll taxes	145,186	141,537	135,177	106,995	130,633
Accrued taxes	15,582	13,604	14,614	16,058	18,488
Current portion of long-term debt, net	5,961	23,044	22,969	22,894	22,007
Operating lease liabilities, current portion	46,756	40,979	38,946	35,324	36,997
Other current liabilities	45,037	31,528	31,457	32,703	30,893
Total current liabilities	632,181	554,622	550,004	506,218	517,433
Deferred income taxes, net	4,389	0	0	0	0
Long-term debt, net	860,306	584,038	589,828	595,598	727,930
Long-term operating lease liabilities	145,569	120,883	118,452	130,426	129,244
Warrant liability	50,467	47,467	52,467	33,000
Other long-term liabilities	30,273	7,410	7,415	7,397	8,601
Total liabilities	1,723,185	1,314,420	1,318,166	1,272,639	1,383,208
Stockholders’ equity:
Preferred stock	0	0	0	0	0
Common stock	9	9	9	9	3
Additional paid-in capital	188,685	186,878	181,888	198,357	101,742
Accumulated deficit	(116,621)	(107,515)	(122,833)	(119,387)	(145,371)
Accumulated other comprehensive income (loss)	1,876	153	(628)	(829)	(134)
Total PAE Incorporated stockholders' equity	73,949	79,525	58,436	78,150	(43,760)
Noncontrolling interests	32,236	35,017	34,430	32,169	31,851
Total liabilities and equity	1,829,370	1,428,962	1,411,032	1,382,958	$ 1,371,299
Previously Reported
Current assets:
Cash and cash equivalents	85,908	145,446	138,469	99,790
Accounts receivable, net	585,511	445,429	432,185	420,765
Prepaid expenses and other current assets	61,607	44,363	45,676	46,760
Total current assets	733,026	635,238	616,330	567,315
Property and equipment, net	27,615	25,696	26,841	28,079
Deferred income taxes, net	0	13,419	12,017	16,597
Investments	18,272	18,961	17,848	17,747
Goodwill	590,668	409,588	409,588	409,588
Intangible assets, net	258,210	156,323	164,370	172,417
Operating lease right-of-use assets, net	191,370	159,975	154,375	161,731
Other noncurrent assets	10,209	9,762	9,663	9,484
Total assets	1,829,370	1,428,962	1,411,032	1,382,958
Current liabilities:
Accounts payable	152,962	140,515	107,154	122,126
Accrued expenses	114,222	103,025	128,992	100,456
Customer advances and billings in excess of costs	106,475	60,390	70,695	69,662
Salaries, benefits and payroll taxes	145,186	141,537	135,177	106,995
Accrued taxes	15,582	13,604	14,614	16,058
Current portion of long-term debt, net	5,961	23,044	22,969	22,894
Operating lease liabilities, current portion	46,756	40,979	38,946	35,324
Other current liabilities	45,037	31,528	31,457	32,703
Total current liabilities	632,181	554,622	550,004	506,218
Deferred income taxes, net	4,389	0	0	0
Long-term debt, net	860,306	584,038	589,828	595,598
Long-term operating lease liabilities	145,569	120,883	118,452	130,426
Warrant liability	0	0	0	0
Other long-term liabilities	30,273	7,410	7,415	7,397
Total liabilities	1,672,718	1,266,953	1,265,699	1,239,639
Stockholders’ equity:
Preferred stock	0	0	0	0
Common stock	9	9	9	9
Additional paid-in capital	252,612	250,805	245,815	262,284
Accumulated deficit	(130,081)	(123,975)	(134,293)	(150,314)
Accumulated other comprehensive income (loss)	1,876	153	(628)	(829)
Total PAE Incorporated stockholders' equity	124,416	126,992	110,903	111,150
Noncontrolling interests	32,236	35,017	34,430	32,169
Total liabilities and equity	1,829,370	1,428,962	1,411,032	1,382,958
Restatement Adjustment
Current assets:
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0	0	0
Prepaid expenses and other current assets	0	0	0	0
Total current assets	0	0	0	0
Property and equipment, net	0	0	0	0
Deferred income taxes, net	0	0	0	0
Investments	0	0	0	0
Goodwill	0	0	0	0
Intangible assets, net	0	0	0	0
Operating lease right-of-use assets, net	0	0	0	0
Other noncurrent assets	0	0	0	0
Total assets	0	0	0	0
Current liabilities:
Accounts payable	0	0	0	0
Accrued expenses	0	0	0	0
Customer advances and billings in excess of costs	0	0	0	0
Salaries, benefits and payroll taxes	0	0	0	0
Accrued taxes	0	0	0	0
Current portion of long-term debt, net	0	0	0	0
Operating lease liabilities, current portion	0	0	0	0
Other current liabilities	0	0	0	0
Total current liabilities	0	0	0	0
Deferred income taxes, net	0	0	0	0
Long-term debt, net	0	0	0	0
Long-term operating lease liabilities	0	0	0	0
Warrant liability	50,467	47,467	52,467	33,000
Other long-term liabilities	0	0	0	0
Total liabilities	50,467	47,467	52,467	33,000
Stockholders’ equity:
Preferred stock	0	0	0	0
Common stock	0	0	0	0
Additional paid-in capital	(63,927)	(63,927)	(63,927)	(63,927)
Accumulated deficit	13,460	16,460	11,460	30,927
Accumulated other comprehensive income (loss)	0	0	0	0
Total PAE Incorporated stockholders' equity	(50,467)	(47,467)	(52,467)	(33,000)
Noncontrolling interests	0	0	0	0
Total liabilities and equity	$ 0	$ 0	$ 0	$ 0