CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock, at Cost	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2016		0	512,000,000
Beginning balance at Dec. 31, 2016	$ 19,747	$ 247	$ 6	$ 18,722	$ 2,703	$ (1,263)	$ (668)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(322)				(322)
Dividends to preferred stockholders	(14)				(14)
Treasury stock purchased (in shares)			(22,000,000)
Treasury stock purchased	(820)			25		(845)
Share-based compensation plans (in shares)			1,000,000
Share-based compensation plans	22			22
Employee stock purchase plan shares purchased	12			12
Total comprehensive income:
Net income	1,652				1,652
Other comprehensive income (loss)	(7)						(7)
Total comprehensive income	1,645				1,652		(7)
Reclassification of tax effects resulting from the 2017 Tax Legislation	(145)				145		(145)
Ending balance (in shares) at Dec. 31, 2017		0	491,000,000
Ending balance at Dec. 31, 2017	20,270	$ 247	$ 6	18,781	4,164	(2,108)	(820)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(471)				(471)
Dividends to preferred stockholders	(29)				(29)
Preferred stock issued (in shares)		1,000,000
Preferred stock issued	$ 593	$ 593
Treasury stock purchased (in shares)	(25,773,807)		(26,000,000)
Treasury stock purchased	$ (1,025)			0		(1,025)
Share-based compensation plans (in shares)			1,000,000
Share-based compensation plans	20			20
Employee stock purchase plan shares purchased	14			14
Total comprehensive income:
Net income	1,721				1,721
Other comprehensive income (loss)	(276)						(276)
Total comprehensive income	1,445				1,721		(276)
Ending balance (in shares) at Dec. 31, 2018		1,000,000	466,000,000
Ending balance at Dec. 31, 2018	20,817	$ 840	$ 6	18,815	5,385	(3,133)	(1,096)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common stockholders	(617)				(617)
Dividends to preferred stockholders	(73)				(73)
Preferred stock issued (in shares)		1,000,000
Preferred stock issued	$ 730	$ 730
Treasury stock purchased (in shares)	(34,305,768)		(34,000,000)
Treasury stock purchased	$ (1,220)			0		(1,220)
Share-based compensation plans (in shares)			1,000,000
Share-based compensation plans	59			59
Employee stock purchase plan shares purchased	17			17
Total comprehensive income:
Net income	1,791				1,791
Other comprehensive income (loss)	680						680
Total comprehensive income	2,471				1,791		680
Ending balance (in shares) at Dec. 31, 2019		2,000,000	433,000,000
Ending balance at Dec. 31, 2019	$ 22,201	$ 1,570	$ 6	$ 18,891	$ 6,498	$ (4,353)	$ (411)