Revenue (Revenue by Product Line) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 5,639	$ 4,913	$ 4,171
Operating Segments | Government Solutions
Disaggregation of Revenue [Line Items]
Revenues	3,925	3,457	2,193
Operating Segments | Government Solutions | Space and Mission Solutions
Disaggregation of Revenue [Line Items]
Revenues	874	651
Operating Segments | Government Solutions | Engineering
Disaggregation of Revenue [Line Items]
Revenues	1,158	1,141
Operating Segments | Government Solutions | Logistics
Disaggregation of Revenue [Line Items]
Revenues	1,893	1,665
Operating Segments | Technology Solutions
Disaggregation of Revenue [Line Items]
Revenues	374	297	269
Operating Segments | Energy Solutions
Disaggregation of Revenue [Line Items]
Revenues	1,339	1,157	1,671
Operating Segments | Energy Solutions | EPC Delivery Solutions
Disaggregation of Revenue [Line Items]
Revenues	438	432
Operating Segments | Energy Solutions | Services and Consulting
Disaggregation of Revenue [Line Items]
Revenues	901	725
Non-strategic Business
Disaggregation of Revenue [Line Items]
Revenues	$ 1	$ 2	$ 38