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, 2015	$ 27,340	$ 3,902	$ 2,603	$ 8,365	$ 13,464	$ (1,028)	$ 34
Beginning balance (in shares) at Dec. 31, 2015		780,337
Add (Deduct):
Net income	2,442				2,426		16
OCI	(104)					(104)
Stock transactions:
Issued in business combinations	1,063	$ 158		905
Issued in business combinations (in shares)		31,665
Issued in connection with equity awards, net	220	$ 46		174
Issued in connection with equity awards, net (in shares)		9,241
Excess tax benefits in connection with equity awards	7			7
Issued in connection with preferred stock offering	450		450
Repurchase of common stock (in shares)		(11,768)
Repurchase of common stock	(520)	$ 59		461
Cash dividends declared on common stock	(925)				(925)
Cash dividends declared on preferred stock	(167)				(167)
Equity-based compensation expense	115			115
Other, net	5			(1)	11		(5)
Ending balance at Dec. 31, 2016	29,926	$ 4,047	3,053	9,104	14,809	(1,132)	45
Ending balance (in shares) at Dec. 31, 2016		809,475
Add (Deduct):
Net income	2,415				2,394		21
OCI	(88)					(88)
Stock transactions:
Issued in business combinations	0
Issued in connection with equity awards, net	120	$ 41		79
Issued in connection with equity awards, net (in shares)		8,059
Repurchase of common stock (in shares)		(35,528)
Repurchase of common stock	(1,613)	$ (178)		(1,435)
Cash dividends declared on common stock	(1,005)				(1,005)
Cash dividends declared on preferred stock	(174)				(174)
Equity-based compensation expense	132			132
Reclassification of certain tax effects	0				247	(247)
Other, net	(18)			13	(12)		(19)
Ending balance at Dec. 31, 2017	$ 29,695	$ 3,910	3,053	7,893	16,259	(1,467)	47
Ending balance (in shares) at Dec. 31, 2017	782,006	782,006
Stock transactions:
Stockholders' Equity Attributable to Noncontrolling Interest	$ 47
Net income	3,257				3,237		20
OCI	(248)					(248)
Issued in business combinations	0
Issued in connection with equity awards, net	(6)	$ 23		(29)
Issued in connection with equity awards, net (in shares)		4,554
Repurchase of common stock (in shares)		(23,234)
Repurchase of common stock	(1,205)	$ (116)		(1,089)
Cash dividends declared on common stock	(1,204)				(1,204)
Cash dividends declared on preferred stock	(174)				(174)
Equity-based compensation expense	141			141
Other, net	(78)			(67)			(11)
Ending balance at Dec. 31, 2018	$ 30,178	$ 3,817	$ 3,053	$ 6,849	$ 18,118	$ (1,715)	$ 56
Ending balance (in shares) at Dec. 31, 2018	763,326	763,326
Stock transactions:
Stockholders' Equity Attributable to Noncontrolling Interest	$ 56