Fair Value Measurement and Fair Value of Financial Instruments (Details 3) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 2,921	$ 4,195
Cash and cash equivalents, Fair Value	2,921	4,195
Cash and cash equivalents	2,921	4,195	3,788	1,174
Held to maturity securities, Carrying Value	2,345	1,273
Held to maturity securities, Fair Value	2,536	1,429
Loans held for investment, net of allowance for loan losses, Carrying value	52,648	51,823
Loans held for investment, net of allowance for loan losses, Fair Value	53,460	52,423
FDIC indemnification asset, carrying value	449	598
FDIC indemnification asset, Fair Value	238	409
Liabilities
Deposits	63,443	64,420
Deposits, Fair Value	63,697	64,420
Interest bearing deposits, Carrying Value	42,666	43,822
Commercial paper and other short-term borrowings, Carrying Value	3,035	3,683
Commercial paper and other short-term borrowings, Fair Value	3,035	3,684
Long-term debt	6,444	6,684
Long-term debt, Fair Value	6,614	6,798
Off-Balance Sheet Instruments
Commitments to extend credit and standby and commercial letters of credit, Carrying amount	285	287
Commitments to extend credit and standby and commercial letters of credit, Fair value	285	287
Level1 [Member]
Assets
Cash and cash equivalents, Fair Value	2,921
Level2 [Member]
Assets
Held to maturity securities, Fair Value	2,536
Liabilities
Deposits, Fair Value	63,697
Commercial paper and other short-term borrowings, Fair Value	3,035
Long-term debt	6,614
Level3 [Member]
Assets
Loans held for investment, net of allowance for loan losses, Fair Value	53,460
FDIC indemnification asset, Fair Value	238
Off-Balance Sheet Instruments
Commitments to extend credit and standby and commercial letters of credit, Fair value	$ 238