Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current income tax expense:
Federal	$ 191	$ 195	$ 257
State	154	89	21
Foreign	1	10	(4)
Total current expense	346	294	274
Deferred income tax expense (benefit):
Federal	(202)	(173)	(49)
State	(61)	(64)	52
Foreign	(1)	(5)	22
Total deferred expense	(264)	(242)	25
Total income tax expense	$ 82	$ 52	$ 299