Summary of Significant Accounting Policies - Schedule of Net Warehouse Interest Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Interest Income Expense Net Line Items
Net warehouse interest income	$ 6,731	$ 4,354
Loans Held for Sale
Interest Income Expense Net Line Items
Warehouse interest income	13,523	7,408
Warehouse interest expense	(8,348)	(4,954)
Net warehouse interest income	5,175	2,454
Loans Held for Investment
Interest Income Expense Net Line Items
Warehouse interest income	2,822	3,057
Warehouse interest expense	(1,266)	(1,157)
Net warehouse interest income	$ 1,556	$ 1,900