Accumulated Other Comprehensive Income Reclassifications out of AOCI (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	$ (2)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Tax	1
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(1)
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax	(114)
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Tax	43
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	(71)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	32
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	(12)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	20		(24)
Net securities gains [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	(2)
Interest Income, Interest and Fees on Loans
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(114)
provision for income taxes [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Tax	1
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Tax	43
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	(12)
employee benefits [Member]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	6
Other Assets And Liabilities, Net [Member]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	$ 26	[1]

[1] This AOCI component is recognized as an adjustment to the funded status of employee benefit plans in the Company's Consolidated Balance Sheets. (For additional information, see Note 15, "Employee Benefit Plans," to the Consolidated Financial Statements in the Company's Annual Report on Form 10−K for the year ended December 31, 2012).