Commitments, Contingencies and Guarantees - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) attorney_general
Commitments and Contingencies Disclosure [Abstract]
Contractual obligation	$ 1,700.0
Other liabilities reserve	$ 1.7
Loss emergence period	1 year
FDIC civil monetary penalties	$ 3.3
Contingency refund (up to)	$ 30.0
Number of state attorney generals | attorney_general	2