Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ in Millions	Total	Preferred Stock [Member]	Preferred Stock [Member] Series A Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series A Preferred Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Retained Earnings [Member] Series A Preferred Stock [Member]	Treasury Stock, at Cost [Member]	Treasury Stock, at Cost [Member] Series A Preferred Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2014		$ 291		$ 1,017		$ 3,986	$ 8,273		$ (2,681)		$ (356)	$ 12
Beginning Balance, Preferred Shares at Dec. 31, 2014		2,905
Beginning Balance, Common Shares at Dec. 31, 2014				859,403
Net income (loss)	$ 474						471					3
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	4										4
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	15										15
Foreign currency translation adjustments, net of income taxes	(13)										(13)
Net pension and postretirement benefit costs, net of income taxes	5										5
Deferred compensation						12
Cash dividends declared on common shares							(119)
Cash dividends declared on Noncumulative Series A Preferred Stock								$ (11)
Common shares repurchased, value									(325)
Common shares repurchased, shares				(22,881)
Series A Preferred Stock exchanged for common shares			$ (1)							$ 1
Series A Preferred Stock exchanged for common shares, Shares			(5)		33
Common shares reissued (returned) for stock options and other employee benefit plans						(100)			121
Common shares reissued (returned) for stock options and other employee benefit plans, shares				7,053
Net contribution from (distribution to) noncontrolling interests												(4)
Ending Balance at Jun. 30, 2015	10,601	$ 290		$ 1,017		3,898	8,614		(2,884)		(345)	11
Ending Balance, Preferred Shares at Jun. 30, 2015		2,900
Ending Balance, Common Shares at Jun. 30, 2015				843,608
Beginning Balance at Dec. 31, 2015	10,759	$ 290		$ 1,017		3,922	8,922		(3,000)		(405)	13
Beginning Balance, Preferred Shares at Dec. 31, 2015		2,900
Beginning Balance, Common Shares at Dec. 31, 2015				835,751
Net income (loss)	389						390					(1)
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	187										187
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	94										94
Foreign currency translation adjustments, net of income taxes	7										7
Net pension and postretirement benefit costs, net of income taxes	3										3
Deferred compensation						(4)
Cash dividends declared on common shares							(135)
Cash dividends declared on Noncumulative Series A Preferred Stock								$ (11)
Common shares reissued (returned) for stock options and other employee benefit plans						(83)			119
Common shares reissued (returned) for stock options and other employee benefit plans, shares				6,952
Net contribution from (distribution to) noncontrolling interests												(7)
Ending Balance at Jun. 30, 2016	$ 11,318	$ 290		$ 1,017		$ 3,835	$ 9,166		$ (2,881)		$ (114)	$ 5
Ending Balance, Preferred Shares at Jun. 30, 2016		2,900
Ending Balance, Common Shares at Jun. 30, 2016				842,703