Income Taxes - Schedule of Components of Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current expense:
Federal	$ 357	$ 629	$ 539
State	97	151	80
Total current expense	454	780	619
Deferred expense:
Federal	290	26	253
State	38	(3)	39
Total deferred expense	328	23	292
Provision for income taxes	$ 782	$ 803	$ 911