Securities (Details 6) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Maturity schedule of securities held to maturity
Due in one year or less, Amortized cost	$ 1
Due after one year through five years, Amortized cost	599
Due after five years through ten years, Amortized cost	988
Due after ten years, Amortized cost	1,095
Total securities held to maturity, Amortized cost	2,683
Due after one year through five years, Carrying Value	500
Due after five years through ten years, Carrying Value	751
Due after ten years, Carrying Value	1,094
Total securities held to maturity, Carrying Value	2,345	1,273
Due in one year or less, Fair Value	1
Due after one year through five years, Fair Value	575
Due after five years through ten years, Fair Value	863
Due after ten years, Fair Value	1,097
Total securities held to maturity, Fair Value	$ 2,536	$ 1,429