Fair Value Disclosures (Carrying Amounts and Fair Values of Financial Assets and Liabilities Not Recorded at Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Securities held to maturity	$ 13,140		$ 14,094
FDIC loss share receivable	656		1,100
Deposits	130,018		124,939
Long-term debt	19,221		21,803
Carrying Amount [Member]
Securities held to maturity	13,140	[1]	14,094	[1]
Loans and leases, excluding covered loans	108,538	[2]	100,495	[2]
Covered loans	3,551	[2]	4,718	[2]
FDIC loss share receivable	656		1,100
Deposits	130,018		124,939
Long-term debt	19,221		21,803
Estimate of Fair Value, Fair Value Disclosure [Member]
Securities held to maturity	13,445	[1]	14,098	[1]
Loans and leases, excluding covered loans	108,505	[2]	100,036	[2]
Covered loans	4,322	[2]	5,706	[2]
FDIC loss share receivable	331		910
Deposits	130,368		125,317
Long-term debt	20,842		23,001
Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities held to maturity	13,407	[1]
Loans and leases, excluding covered loans	0	[2]
Covered loans	0	[2]
FDIC loss share receivable	0
Deposits	130,368
Long-term debt	20,842
Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Securities held to maturity	38	[1]
Loans and leases, excluding covered loans	108,505	[2]
Covered loans	4,322	[2]
FDIC loss share receivable	331
Deposits	0
Long-term debt	$ 0

[1] The carrying value excludes amounts deferred in other comprehensive income resulting from the transfer of securities available for sale to securities held to maturity.

[2] The carrying value is net of the allowance for loan and lease losses.