Mortgage Servicing Rights (Details 1) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012 Age Y Basis_Points Multiple	Mar. 31, 2012	Dec. 31, 2011 Basis_Points Multiple Y Age	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
MSRs and related characteristics by portfolio
Servicing portfolio	$ 207,427		$ 191,082
Fair market value	1,594	1,737	1,519	1,989	2,073	1,837
Value (bps)	77		79
Weighted-average servicing fees (bps)	31		31
Multiple (value/servicing fees)	2.48		2.55
Weighted-average note rate	4.79%		5.03%
Age (in years)	2.7		2.8
Expected prepayment (constant prepayment rate)	21.70%		21.30%
Expected life (in years)	3.9		4.0
Discount rate	10.40%		10.40%
MRBP [Member]
MSRs and related characteristics by portfolio
Servicing portfolio	13,697		13,357
Fair market value	155		155
Value (bps)	113		116
Weighted-average servicing fees (bps)	40		40
Multiple (value/servicing fees)	2.83		2.90
Weighted-average note rate	5.34%		5.50%
Age (in years)	4.3		4.2
Expected prepayment (constant prepayment rate)	13.20%		12.90%
Expected life (in years)	6.1		6.4
Discount rate	12.10%		12.10%
Government [Member]
MSRs and related characteristics by portfolio
Servicing portfolio	36,455		32,567
Fair market value	304		290
Value (bps)	83		89
Weighted-average servicing fees (bps)	34		36
Multiple (value/servicing fees)	2.44		2.47
Weighted-average note rate	4.81%		5.08%
Age (in years)	2.4		2.5
Expected prepayment (constant prepayment rate)	21.20%		21.10%
Expected life (in years)	4.1		4.0
Discount rate	11.30%		11.30%
Conventional Loan [Member]
MSRs and related characteristics by portfolio
Servicing portfolio	157,275		145,158
Fair market value	$ 1,135		$ 1,074
Value (bps)	72		74
Weighted-average servicing fees (bps)	30		29
Multiple (value/servicing fees)	2.40		2.55
Weighted-average note rate	4.74%		4.97%
Age (in years)	2.6		2.8
Expected prepayment (constant prepayment rate)	22.60%		22.10%
Expected life (in years)	3.7		3.8
Discount rate	10.00%		10.00%