Guarantee Arrangements and Pledged Assets (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Trend in repurchase demands received on loans sold to GSEs and other third parties by loan origination vintage
Pre - 2004	$ 2	$ 2	$ 3	$ 3
2004	7	4	11	9
2005	9	6	14	14
2006	29	10	45	23
2007	76	31	120	70
2008	52	30	78	58
Post 2008	6	22	10	46
Total repurchase demands received	$ 181	$ 105	$ 281	$ 223