Guaranty Obligation and Allowance for Risk-Sharing Obligations - Summary of Allowance for Risk-Sharing Obligations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
GUARANTY OBLIGATION AND ALLOWANCE FOR RISK-SHARING OBLIGATIONS
Beginning balance	$ 5,149	$ 4,054	$ 5,586	$ 3,904
Provision for risk-sharing obligations	275	58	121	208
Write-offs		(808)		(808)
Other	386		103
Ending balance	5,810	$ 3,304	5,810	$ 3,304
Maximum quantifiable contingent liability associated with guarantees	$ 4,300,000		$ 4,300,000