FAIR VALUE MEASUREMENTS - Schedule of Carrying Amounts and the Fair Values of the Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Financial assets:
Cash and cash equivalents	$ 50,745	$ 118,756	$ 98,224	$ 136,988
Restricted cash	9,313	9,861	10,006	5,306
Pledged securities	86,900	84,850	$ 75,225	$ 72,190
Loans held for sale	1,230,311	1,858,358
Loans held for investment, net	311,242	220,377
Derivative assets	15,446	61,824
Financial liabilities:
Derivative liabilities	9,449	4,396
Warehouse notes payable	1,406,462	1,990,183
Note payable	164,088	164,163
Carrying Amount
Financial assets:
Cash and cash equivalents	50,745	118,756
Restricted cash	9,313	9,861
Pledged securities	86,900	84,850
Loans held for sale	1,230,311	1,858,358
Loans held for investment, net	311,242	220,377
Derivative assets	15,446	61,824
Total financial assets	1,703,957	2,354,026
Financial liabilities:
Derivative liabilities	9,449	4,396
Warehouse notes payable	1,406,462	1,990,183
Note payable	164,088	164,163
Total financial liabilities	1,579,999	2,158,742
Fair Value
Financial assets:
Cash and cash equivalents	50,745	118,756
Restricted cash	9,313	9,861
Pledged securities	86,900	84,850
Loans held for sale	1,230,311	1,858,358
Loans held for investment, net	313,355	222,313
Derivative assets	15,446	61,824
Total financial assets	1,706,070	2,355,962
Financial liabilities:
Derivative liabilities	9,449	4,396
Warehouse notes payable	1,407,696	1,992,111
Note payable	167,051	167,327
Total financial liabilities	$ 1,584,196	$ 2,163,834