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	1,100				1,096		4
OCI	59					59
Stock transactions:
Issued in connection with equity awards, net	88	$ 33		55
Issued in connection with equity awards, net (in shares)		6,644
Repurchase of common stock	(320)	$ (40)		(280)
Repurchase of common stock (in shares)		(8,026)
Cash dividends declared on common stock	(485)				(485)
Cash dividends declared on preferred stock	(87)				(87)
Equity-based compensation expense	74			74
Other, net	(6)			13	(12)		(7)
Ending balance at Jun. 30, 2017	30,349	$ 4,040	3,053	8,966	15,321	(1,073)	42
Ending balance (in shares) at Jun. 30, 2017		808,093
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	$ 1,613				1,607		6
OCI	(239)					(239)
Stock transactions:
Issued in connection with equity awards, net	(2)	$ 20		(22)
Issued in connection with equity awards, net (in shares)		4,055
Repurchase of common stock	(630)	$ (58)		(572)
Repurchase of common stock (in shares)		(11,614)
Cash dividends declared on common stock	(582)				(582)
Cash dividends declared on preferred stock	(87)				(87)
Equity-based compensation expense	76			76
Other, net	(12)			(11)			(1)
Ending balance at Jun. 30, 2018	$ 29,832	$ 3,872	$ 3,053	$ 7,364	$ 17,197	$ (1,706)	$ 52
Ending balance (in shares) at Jun. 30, 2018	774,447	774,447