Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment		Adjusted Balance	Common Stock (Par Value: $0.01)	Preferred Stock (Par Value: $0.01)	Paid-in Capital in Excess of Par	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment		Retained Earnings Adjusted Balance	Treasury Stock, at Cost	Accumulated Other Comprehensive Loss, Net of Tax
Balance at Dec. 31, 2018	$ 6,655				$ 5	$ 503	$ 6,100	$ 297				$ (162)	$ (88)
Balance, shares at Dec. 31, 2018					473,536,604
Shares issued for restricted stock, net of forfeitures							(17)					17
Shares issued for restricted stock, net of forfeitures, shares					1,665,028
Compensation expense related to restricted stock awards	32						32
Net income	395							395
Dividends paid on common stock ($0.68)	(317)							(317)
Dividends paid on preferred stock ($63.76)	(33)							(33)
Purchase of common stock	(75)							0				(75)
Purchase of common stock, shares					(7,854,851)
Other comprehensive income (loss), net of tax	55												55
Balance at Dec. 31, 2019	$ 6,712	$ (10)	[1]	$ 6,702	$ 5	503	6,115	342	$ (10)	[1]	$ 332	(220)	(33)
Balance, shares at Dec. 31, 2019					467,346,781
Accounting Standards Update [Extensible List]	Accounting Standards Update 2016-13	Accounting Standards Update 2016-13							Accounting Standards Update 2016-13
Shares issued for restricted stock, net of forfeitures							(22)					22
Shares issued for restricted stock, net of forfeitures, shares					2,321,105
Compensation expense related to restricted stock awards	$ 30						30
Net income	511							511
Dividends paid on common stock ($0.68)	(316)							(316)
Dividends paid on preferred stock ($63.76)	(33)							(33)
Purchase of common stock	(60)											(60)
Purchase of common stock, shares					(5,766,078)
Other comprehensive income (loss), net of tax	8												8
Balance at Dec. 31, 2020	6,842				$ 5	503	6,123	494				(258)	(25)
Balance, shares at Dec. 31, 2020					463,901,808
Shares issued for restricted stock, net of forfeitures							(28)					28
Shares issued for restricted stock, net of forfeitures, shares					2,515,942
Compensation expense related to restricted stock awards	31						31
Net income	596							596
Dividends paid on common stock ($0.68)	(316)							(316)
Dividends paid on preferred stock ($63.76)	(33)							(33)
Purchase of common stock	(16)											(16)
Purchase of common stock, shares					(1,402,107)
Other comprehensive income (loss), net of tax	(60)												(60)
Balance at Dec. 31, 2021	$ 7,044				$ 5	$ 503	$ 6,126	$ 741				$ (246)	$ (85)
Balance, shares at Dec. 31, 2021					465,015,643

[1] Amount represents a $10 million cumulative adjustment, net of tax, to retained earnings as of January 1, 2020, as a result of the adoption of ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which became effective January 1, 2020.