Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Preferred Stock	Additional Paid-In Capital	Retained Earnings	AOCI	Noncontrolling Interests
Beginning balance at Dec. 31, 2016	$ 29,926	$ 4,047	$ 3,053	$ 9,104	$ 14,809	$ (1,132)	$ 45
Beginning balance (in shares) at Dec. 31, 2016		809,475
Add (Deduct):
Net income	426				421		5
OCI	7					7
Stock transactions:
Issued in connection with equity awards, net	86	$ 32		54
Issued in connection with equity awards, net (in shares)		6,256
Repurchase of common stock	(160)	$ (22)		(138)
Repurchase of common stock (in shares)		(4,361)
Cash dividends declared on common stock	(243)				(243)
Cash dividends declared on preferred stock	(43)				(43)
Equity-based compensation expense	30			30
Other, net	(4)			13	(11)		(6)
Ending balance at Mar. 31, 2017	30,025	$ 4,057	3,053	9,063	14,933	(1,125)	44
Ending balance (in shares) at Mar. 31, 2017		811,370
Beginning balance at Dec. 31, 2017	$ 29,695	$ 3,910	3,053	7,893	16,259	(1,467)	47
Beginning balance (in shares) at Dec. 31, 2017	782,006	782,006
Add (Deduct):
Net income	$ 791				788		3
OCI	(178)					(178)
Stock transactions:
Issued in connection with equity awards, net	(13)	$ 18		(31)
Issued in connection with equity awards, net (in shares)		3,599
Repurchase of common stock	(320)	$ (29)		(291)
Repurchase of common stock (in shares)		(5,853)
Cash dividends declared on common stock	(292)				(292)
Cash dividends declared on preferred stock	(43)				(43)
Equity-based compensation expense	31			31
Other, net	(9)			(9)
Ending balance at Mar. 31, 2018	$ 29,662	$ 3,899	$ 3,053	$ 7,593	$ 16,712	$ (1,645)	$ 50
Ending balance (in shares) at Mar. 31, 2018	779,752	779,752