Fair Value of Assets and Liabilities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market servicing rates of products on outstanding principal	0.50%	0.50%
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market servicing rates of products on outstanding principal	0.50%	0.50%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Market servicing rates of products on outstanding principal	0.75%	0.75%