Securities (Schedule of Non-Investment Grade Securities with Significant Unrealized Losses) (Details) (RMBS 1 [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012
RMBS 1 [Member]
Non-investment grade securities, amortized cost	$ 124
Non-investment grade securities, cumulative credit loss recognized	(33)
Non-investment grade securities, adjusted amortized cost	91
Non-investment grade securities, fair value	76
Non-investment grade securities, unrealized loss	$ (15)