Revenue - Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenue from customers	$ 4,018	$ 5,403	$ 12,576	$ 12,569
All other revenue	90	456	1,073	1,714
Revenues, Total	$ 4,108	$ 5,859	$ 13,649	$ 14,283