Mortgage Servicing Rights - MSRs and Related Characteristics by Portfolio (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014 BasisPoint Multiple	Dec. 31, 2013 Multiple BasisPoint	Mar. 31, 2013	Dec. 31, 2012
Servicing Assets at Fair Value [Line Items]
Servicing portfolio	$ 224,637	$ 226,842
Fair value	2,618	2,680	1,955	1,700
Value (bps)	117	118
Weighted-average servicing fees (bps)	30	30
Multiple (value/servicing fees)	3.90	3.93
Weighted-average note rate	4.21%	4.22%
Weighted-average age (in years)	2 years 9 months 18 days	2 years 7 months 6 days
Weighted-average expected prepayment (constant prepayment rate)	11.40%	11.20%
Weighted-average expected life (in years)	6 years 10 months 24 days	7 years 1 month 6 days
Weighted-average discount rate	10.20%	10.20%
MRBP [Member]
Servicing Assets at Fair Value [Line Items]
Servicing portfolio	16,459	15,896
Fair value	188	180
Value (bps)	114	113
Weighted-average servicing fees (bps)	39	39
Multiple (value/servicing fees)	2.92	2.90
Weighted-average note rate	4.67%	4.70%
Weighted-average age (in years)	3 years 9 months 18 days	3 years 9 months 18 days
Weighted-average expected prepayment (constant prepayment rate)	13.30%	13.50%
Weighted-average expected life (in years)	6 years 2 months 12 days	6 years 2 months 12 days
Weighted-average discount rate	11.90%	11.90%
Government [Member]
Servicing Assets at Fair Value [Line Items]
Servicing portfolio	41,550	41,659
Fair value	485	500
Value (bps)	117	120
Weighted-average servicing fees (bps)	32	32
Multiple (value/servicing fees)	3.66	3.75
Weighted-average note rate	4.23%	4.24%
Weighted-average age (in years)	2 years 9 months 18 days	2 years 7 months 6 days
Weighted-average expected prepayment (constant prepayment rate)	11.80%	11.50%
Weighted-average expected life (in years)	6 years 8 months 12 days	6 years 10 months 24 days
Weighted-average discount rate	11.20%	11.20%
Conventional [Member]
Servicing Assets at Fair Value [Line Items]
Servicing portfolio	166,628	169,287
Fair value	$ 1,945	$ 2,000
Value (bps)	117	118
Weighted-average servicing fees (bps)	29	29
Multiple (value/servicing fees)	4.03	4.07
Weighted-average note rate	4.16%	4.17%
Weighted-average age (in years)	2 years 8 months 12 days	2 years 6 months
Weighted-average expected prepayment (constant prepayment rate)	11.10%	10.90%
Weighted-average expected life (in years)	7 years	7 years 2 months 12 days
Weighted-average discount rate	9.80%	9.80%