Segment Information - Summary of Revenues by Business Lines (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 970,993	$ 904,405
Federal Solution Segment
Segment Reporting Information [Line Items]
Revenues	477,571	422,812
Federal Solution Segment | Space & Geospatial Solutions
Segment Reporting Information [Line Items]
Revenues	51,288	45,757
Federal Solution Segment | Cyber & Intelligence
Segment Reporting Information [Line Items]
Revenues	98,882	72,549
Federal Solution Segment | Engineered Systems
Segment Reporting Information [Line Items]
Revenues	172,832	145,618
Federal Solution Segment | Missile Defense & C5ISR
Segment Reporting Information [Line Items]
Revenues	154,569	158,888
Critical Infrastructure
Segment Reporting Information [Line Items]
Revenues	493,422	481,593
Critical Infrastructure | Connected Communities
Segment Reporting Information [Line Items]
Revenues	101,901	107,613
Critical Infrastructure | Mobility Solutions
Segment Reporting Information [Line Items]
Revenues	$ 391,521	$ 373,980