Guaranty Obligation and Allowance for Risk-Sharing Obligations - Summary of Allowance for Risk-Sharing Obligations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Risk-Sharing Contracts
Beginning balance	$ 3,904	$ 7,363
Provision for risk-sharing obligations	1,680	1,783	$ 881
Other	810
Ending balance	5,586	3,904	$ 7,363
Transfers to allowance, watch list loans		1,000
Fannie Mae DUS program
Allowance for Risk-Sharing Contracts
Maximum quantifiable contingent liability associated with guarantees	$ 4,100,000	$ 4,100,000