Intangible Assets - Schedule of Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	$ 206	$ 295
Mortgage servicing rights [Member]
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	159	237
Purchased credit card relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	47	54
Favorable lease agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	0	4
Residential Mortgage [Member] | Mortgage servicing rights [Member]
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	159	227
Commercial [Member] | Mortgage servicing rights [Member]
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	$ 0	$ 10