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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Aggregate fair value	$ 229,653		$ 229,653		$ 166,247
Aggregate unpaid principal	219,967		219,967		161,083
Aggregate fair value less unpaid principal	9,686		9,686		$ 5,164
Net gain (loss) on change in Fair Value	$ 2,000	$ 3,100	$ 3,900	$ 3,700