Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ in Millions	Total	Preferred Stock [Member]	Common Shares [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock, at Cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]	Series A Preferred Stock [Member] Preferred Stock [Member]	Series A Preferred Stock [Member] Common Shares [Member]	Series A Preferred Stock [Member] Retained Earnings [Member]	Series A Preferred Stock [Member] Treasury Stock, at Cost [Member]
Beginning Balance at Dec. 31, 2013		$ 291	$ 1,017	$ 4,022	$ 7,606	$ (2,281)	$ (352)	$ 17
Beginning Balance, Preferred Shares at Dec. 31, 2013		2,905
Beginning Balance, Common Shares at Dec. 31, 2013			890,724
Net income (loss)	$ 653				647			6
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	24						24
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	(4)						(4)
Foreign currency translation adjustments, net of income taxes	(12)						(12)
Net pension and postretirement benefit costs, net of income taxes	19						19
Cash dividends declared on common shares					(161)
Cash dividends declared on Noncumulative Series A Preferred Stock											$ (17)
Common shares repurchased, value						(355)
Common shares repurchased, shares			(26,499)
Common shares reissued (returned) for stock options and other employee benefit plans				(38)		73
Common shares reissued (returned) for stock options and other employee benefit plans, shares			4,252
LIHTC guaranteed funds put					7
Net contribution from (distribution to) noncontrolling interests								(6)
Ending Balance at Sep. 30, 2014	10,503	$ 291	$ 1,017	3,984	8,082	(2,563)	(325)	17
Ending Balance, Preferred Shares at Sep. 30, 2014		2,905
Ending Balance, Common Shares at Sep. 30, 2014			868,477
Beginning Balance at Dec. 31, 2014	10,542	$ 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)	691				690			1
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	58						58
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	63						63
Foreign currency translation adjustments, net of income taxes	(18)						(18)
Net pension and postretirement benefit costs, net of income taxes	(19)						(19)
Deferred compensation				13
Cash dividends declared on common shares					(182)
Cash dividends declared on Noncumulative Series A Preferred Stock											$ (17)
Common shares repurchased, value						(448)
Common shares repurchased, shares			(31,267)
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				(85)		120
Common shares reissued (returned) for stock options and other employee benefit plans, shares			7,116
Net contribution from (distribution to) noncontrolling interests								(1)
Ending Balance at Sep. 30, 2015	$ 10,717	$ 290	$ 1,017	$ 3,914	$ 8,764	$ (3,008)	$ (272)	$ 12
Ending Balance, Preferred Shares at Sep. 30, 2015		2,900
Ending Balance, Common Shares at Sep. 30, 2015			835,285