Deposits and Borrowings - Schedule of Components of Interest Expense on Short-Term Borrowings and Long-Term Debt (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Short-term borrowings:
Federal funds purchased and securities loaned or sold under agreements to repurchase	$ 0	$ 0	$ 1	$ 1
FHLB advances	0	6	9	15
Total short-term borrowings	0	6	10	16
Long-term debt:
Securitized debt obligations	39	32	108	109
Senior and subordinated notes	82	71	241	226
Other long-term borrowings	12	10	29	20
Total long-term debt	133	113	378	355
Total interest expense	$ 133	$ 119	$ 388	$ 371