Contracts with Customers - Summary of Remaining Unsatisfied Performance Obligations Expect to Satisfy (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 5,100,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 3,011,017
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,083,193
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,029,840
Revenue, remaining performance obligation, expected timing of satisfaction, period
Federal Solution Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,319,438
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Federal Solution Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 550,073
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Federal Solution Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 315,965
Revenue, remaining performance obligation, expected timing of satisfaction, period
Critical Infrastructure | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 1,691,579
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Critical Infrastructure | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 533,120
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Critical Infrastructure | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining unsatisfied performance obligations	$ 713,875
Revenue, remaining performance obligation, expected timing of satisfaction, period