CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Loss	Preferred Class A	Preferred Class A Retained Earnings (Accumulated Deficit)	Preferred Class B	Preferred Class B Retained Earnings (Accumulated Deficit)
Balance, at Dec. 31, 2016	$ 6,272	$ 394	$ 3	$ 6,921	$ (909)	$ (137)
Balance, (in shares) at Dec. 31, 2016			274.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	3				3
Net income	614				614
Other comprehensive income (loss)	111					111
Issuance of preferred stock - Series B	295								$ 295
Preferred stock dividend declared	(25)						$ (25)	$ (25)
Repurchases of common stock, shares			(9.0)
Repurchases of common stock	(362)			(362)
Share-based compensation	41			41
Other common stock activity, shares			2.0
Other common stock activity	(18)			(18)
Balance, at Dec. 31, 2017	6,931	689	$ 3	6,582	(317)	(26)
Balance, (in shares) at Dec. 31, 2017			267.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change | Hedge accounting adoption					7	(7)
Cumulative effect of accounting change | Reclassification of tax effects due to federal tax reform					14	(14)
Net income	1,052				1,052
Other comprehensive income (loss)	(228)					(228)
Common stock dividends	(36)				(36)
Preferred stock dividend declared	(36)						(24)	(24)	(12)	$ (12)
Repurchases of common stock, shares			(22.0)
Repurchases of common stock	(1,140)		$ (1)	(1,139)
Share-based compensation	46			46
Other common stock activity, shares			1.0
Other common stock activity	(27)			(27)
Balance, at Dec. 31, 2018	6,562	689	$ 2	5,462	684	(275)
Balance, (in shares) at Dec. 31, 2018			246.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	955				955
Other comprehensive income (loss)	247					247
Common stock dividends	(135)				(135)
Preferred stock dividend declared	(40)						$ (24)	$ (24)	$ (16)	$ (16)
Repurchases of common stock, shares			(24.8)
Repurchases of common stock	(1,085)		$ (1,100)	(1,085)
Share-based compensation	53			53
Other common stock activity, shares			2.0
Other common stock activity	(14)			(14)
Balance, at Dec. 31, 2019	$ 6,543	$ 689	$ 2	$ 4,416	$ 1,464	$ (28)
Balance, (in shares) at Dec. 31, 2019			223.0