Revenue from Contracts with Customers (Tables)

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Revenue by Contract Type [Table Text Block]

	Three months ended March 31,
	2021		2020
Cost-reimbursable	$	419,775	$	418,655
Fixed-price	132,208		121,555
Time-and-materials	81,241		70,702
Revenue	$	633,224	$	610,912

Revenue by Customer [Table Text Block]

	Three months ended March 31,
	2021		2020
U.S. Government	$	628,498	$	600,528
State agencies, international agencies and commercial entities	4,726		10,384
Revenue	$	633,224	$	610,912

Revenue by Contractor Type [Table Text Block]

	Three months ended March 31,
	2021		2020
Prime contractor	$	589,074	$	555,168
Subcontractor	44,150		55,744
Revenue	$	633,224	$	610,912

Schedule Of Contract Receivables [Table Text Block]

The components of our receivables are as follows (in thousands):

	March 31, 2021		December 31, 2020
Billed receivables	$	318,417	$	312,991
Unbilled receivables	128,099		106,007
Allowance for doubtful accounts	(17,761)		(18,377)
Receivables—net	$	428,755	$	400,621

Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]

The following table discloses when we expect to recognize the remaining performance obligation as revenue (in billions):

For the remaining nine months ending December 31, 2021		For the year ending
		December 31, 2022		December 31, 2023		Thereafter
$	1.5	$	0.4	$	0.2	$	0.5