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	1,799				1,790		9
Net change in AOCI	278					278
Stock transactions:
Issued in business combinations	1,063	$ 158		905
Issued in business combinations (in shares)		31,666
Issued in connection with equity awards, net	24	$ 18		6
Issued in connection with equity awards, net (in shares)		3,715
Repurchase of common stock	(160)	$ (21)		(139)
Repurchase of common stock (in shares)		(4,294)
Issued in connection with preferred stock offerings	450		450
Cash dividends declared on common stock	(682)				(682)
Cash dividends declared on preferred stock	(123)				(123)
Equity-based compensation expense	96			96
Other, net	6			0	10		(4)
Ending balance at Sep. 30, 2016	30,091	$ 4,057	3,053	9,233	14,459	(750)	39
Ending balance (in shares) at Sep. 30, 2016		811,424
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	809,475
Add (Deduct):
Net income	$ 1,748				1,736		12
Net change in AOCI	96					96
Stock transactions:
Issued in business combinations	0
Issued in connection with equity awards, net	104	$ 37		67
Issued in connection with equity awards, net (in shares)		7,201
Repurchase of common stock	(1,240)	$ (139)		(1,101)
Repurchase of common stock (in shares)		(27,755)
Issued in connection with preferred stock offerings	0
Cash dividends declared on common stock	(747)				(747)
Cash dividends declared on preferred stock	(130)				(130)
Equity-based compensation expense	109			109
Other, net	(13)			13	(12)		(14)
Ending balance at Sep. 30, 2017	$ 29,853	$ 3,945	$ 3,053	$ 8,192	$ 15,656	$ (1,036)	$ 43
Ending balance (in shares) at Sep. 30, 2017	788,921	788,921