Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	$ 36	$ 181
Purchased credit card relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	36	41
Residential Mortgage [Member] | Mortgage servicing rights [Member]
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	$ 0	$ 140