Fair Value Measurements (Details 1) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
The difference between the carrying amount of Mortgage loans held for sale measured at fair value, and the aggregate unpaid principal amount that the Company is contractually entitled to receive at maturity
Carrying amount, Total	$ 1,707	$ 4,329
Fair Value, Measurements, Recurring [Member]
The difference between the carrying amount of Mortgage loans held for sale measured at fair value, and the aggregate unpaid principal amount that the Company is contractually entitled to receive at maturity
Carrying amount, Total	1,707	4,329
Carrying amount, Loans 90 or more days past due and on non-accrual status	16	14
Aggregate unpaid principal balance, Total	1,689	4,356
Aggregate unpaid principal balance, Loans 90 or more days past due and on non-accrual status	24	21
Difference, Total	18	(27)
Difference, Loans 90 or more days past due and on non-accrual status	$ (8)	$ (7)