Parent Company Financial Statements (Parent Company Statement Of Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net cash provided by (used in) operating activities	$ 1,826	$ 3,374	$ 823
Net decrease (increase) in interest-bearing deposits with banking subsidiary	8,123	(36,652)	4,398
Proceeds from sales and maturities of available-for-sale securities	44,375	44,810	34,250
Business acquisitions	(511)	(214)	(2,332)
Net cash provided by (used in) investing activities	(4,591)	(53,895)	3,192
Net decrease in short-term borrowings	(1,587)	(8,555)	(11,233)
Proceeds from issuance of long-term debt, net of issuance costs	998	1,986	0
Payments for long-term debt	(1,781)	(2,486)	(341)
Proceeds from issuance of preferred stock, net of issuance costs	488	500	0
Proceeds related to common stock awards and option exercises	154	49	10
Purchases of common stock	(1,440)	(675)	0
Repurchases of common stock for employee tax withholding	(101)	(63)	(44)
Payments for cash dividends	(463)	(295)	(20)
Net cash provided by (used in) financing activities	3,162	49,403	(3,345)
Net increase (decrease)	397	(1,118)	670
Cash and due from banks at beginning of year	2,193	3,311	2,641
Cash and due from banks at end of year	2,590	2,193	3,311
Parent Company [Member]
Net cash provided by (used in) operating activities	2,605	(571)	1,453
Net decrease (increase) in interest-bearing deposits with banking subsidiary	1,115	144	(831)
Proceeds from sales and maturities of available-for-sale securities	0	0	1
Investments in non-banking subsidiaries and unconsolidated entities	(68)	(648)	(277)
Sale of investment in non-banking subsidiaries and unconsolidated entities	28	39	127
Business acquisitions	(2)	(51)	(141)
Net cash provided by (used in) investing activities	1,073	(516)	(1,121)
Net decrease in short-term borrowings	(500)	0	0
Net (decrease) increase in commercial paper	(66)	(415)	22
Proceeds from issuance of long-term debt, net of issuance costs	0	1,986	0
Payments for long-term debt	(1,750)	0	(300)
Proceeds from issuance of preferred stock, net of issuance costs	488	500	0
Proceeds related to common stock awards and option exercises	154	49	10
Purchases of common stock	(1,440)	(675)	0
Repurchases of common stock for employee tax withholding	(101)	(63)	(44)
Payments for cash dividends	(463)	(295)	(20)
Net cash provided by (used in) financing activities	(3,678)	1,087	(332)
Net increase (decrease)	0	0	0
Cash and due from banks at beginning of year	0	0	0
Cash and due from banks at end of year	$ 0	$ 0	$ 0