Investments (Details Textuals 21) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Variable Interest Entity [Line Items]
Remaining years to repayment of long-term debt held by consolidated securitization entities			4 years
Consolidated Securitization Entities [Member]
Variable Interest Entity [Line Items]
Variable interest, maximum exposure to loss in consolidated securitization entities	$ 177		$ 177		$ 172
Long-term debt held by consolidated securitization entities, percentage range minimum	2.25%		2.25%
Long-term debt held by consolidated securitization entities, percentage range maximum	5.57%		5.57%
Interest expense on long-term debt held by consolidated securitization entities	$ 42	$ 92	$ 85	$ 184