Consolidated Statements of Changes in Equity (USD $) In Millions, except Share data in Thousands, unless otherwise specified	Total	Preferred Stock [Member]	Common Shares [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Retained Earnings [Member] Series A Preferred Stock [Member]	Treasury Stock, at Cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2011		$ 291	$ 1,017	$ 4,194	$ 6,246		$ (1,815)	$ (28)	$ 17
Beginning Balance, Common Shares at Dec. 31, 2011			953,008
Beginning Balance, Preferred Shares at Dec. 31, 2011		2,905
Net income (loss)	662				655				7
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	(81)							(81)
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	28							28
Foreign currency translation adjustments, net of income taxes	5							5
Net pension and postretirement benefit costs, net of income taxes	7							7
Deferred compensation				10
Cash dividends declared on common shares					(123)
Cash dividends declared on Noncumulative Series A Preferred Stock						(16)
Common shares repurchased, value							(163)
Common shares repurchased, shares			(20,107)
Common shares reissued (returned) for stock options and other employee benefit plans				(86)			110
Common shares reissued (returned) for stock options and other employee benefit plans, shares			3,294
Net contribution from (distribution to) noncontrolling interests									4
Ending Balance at Sep. 30, 2012	10,279	291	1,017	4,118	6,762		(1,868)	(69)	28
Ending Balance, Common Shares at Sep. 30, 2012			936,195
Ending Balance, Preferred Shares at Sep. 30, 2012		2,905
Beginning Balance at Dec. 31, 2012	10,309	291	1,017	4,126	6,913		(1,952)	(124)	38
Beginning Balance, Common Shares at Dec. 31, 2012			925,769
Beginning Balance, Preferred Shares at Dec. 31, 2012		2,905
Net income (loss)	680				680
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	(228)							(228)
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	(29)							(29)
Foreign currency translation adjustments, net of income taxes	(12)							(12)
Net pension and postretirement benefit costs, net of income taxes	24							24
Deferred compensation				3
Cash dividends declared on common shares					(145)
Cash dividends declared on Noncumulative Series A Preferred Stock						(17)
Common shares repurchased, value							(375)
Common shares repurchased, shares			(33,940)
Common shares reissued (returned) for stock options and other employee benefit plans				(100)			134
Common shares reissued (returned) for stock options and other employee benefit plans, shares			5,992
Net contribution from (distribution to) noncontrolling interests									(8)
Ending Balance at Sep. 30, 2013	$ 10,236	$ 291	$ 1,017	$ 4,029	$ 7,431		$ (2,193)	$ (369)	$ 30
Ending Balance, Common Shares at Sep. 30, 2013			897,821
Ending Balance, Preferred Shares at Sep. 30, 2013		2,905