Commitments, Contingencies and Guarantees - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2016 USD ($) attorney_general	May 13, 2014 USD ($)
Loss Contingencies [Line Items]
Contractual obligation	$ 1,800,000,000
Other liabilities reserve	$ 1,600,000
Loss contingency, loss emergence period	1 year
FDIC civil monetary penalties		$ 3,300,000
Number of Attorney Generals | attorney_general	2
Maximum
Loss Contingencies [Line Items]
Contingency refund (up to)		$ 30,000,000