Fair Value Measurements - Summary of Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance for Mortgage Loans Held for Sale (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Aggregate fair value	$ 192,545		$ 166,247
Aggregate unpaid principal	185,483		161,083
Aggregate fair value less unpaid principal	7,062		$ 5,164
Net gain (loss) on change in Fair Value	$ 1,900	$ 1,900