Revenues - Geographic Areas (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 821	$ 1,309	$ 2,036	$ 2,655
Western Hemisphere
Disaggregation of Revenue [Line Items]
Revenue	310	719	898	1,445
Western Hemisphere | North America
Disaggregation of Revenue [Line Items]
Revenue	172	420	513	876
Western Hemisphere | Latin America
Disaggregation of Revenue [Line Items]
Revenue	138	299	385	569
Eastern Hemisphere
Disaggregation of Revenue [Line Items]
Revenue	511	590	1,138	1,210
Eastern Hemisphere | Middle East & North Africa and Asia
Disaggregation of Revenue [Line Items]
Revenue	341	362	744	752
Eastern Hemisphere | Europe/Sub-Sahara Africa/Russia
Disaggregation of Revenue [Line Items]
Revenue	$ 170	$ 228	$ 394	$ 458