Premises and Equipment Leases (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 214
Capital Leases, Future Minimum Payments Due, Next Twelve Months	2
Operating Leases, Future Minimum Payments, Due in Two Years	202
Capital Leases, Future Minimum Payments Due in Two Years	2
Operating Leases, Future Minimum Payments, Due in Three Years	185
Capital Leases, Future Minimum Payments Due in Three Years	2
Operating Leases, Future Minimum Payments, Due in Four Years	177
Capital Leases, Future Minimum Payments Due in Four Years	2
Operating Leases, Future Minimum Payments, Due in Five Years	154
Capital Leases, Future Minimum Payments Due in Five Years	2
Operating Leases, Future Minimum Payments, Due Thereafter	377
Capital Leases, Future Minimum Payments Due Thereafter	5
Operating Leases, Future Minimum Payments Due	1,309
Capital Leases, Future Minimum Payments Due	15
Capital Leases, Future Minimum Payments, Interest Included in Payments	4
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	$ 11	[1]

[1] Amounts do not include accrued interest.