Income Taxes - Provision for income taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 204	$ 272	$ (9)
State	12	18	3
Foreign	9	8	0
Total current	225	298	(6)
Deferred:
Federal	5	(3)	(85)
State	6	(3)	(9)
Foreign	(1)	0	0
Total deferred	10	(6)	(94)
Income tax expense (benefit)	$ 235	$ 292	$ (100)