FAIR VALUE MEASUREMENTS - Schedule of Carrying Amounts and the Fair Values of the Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financial assets:
Cash and cash equivalents	$ 305,635	$ 321,097	$ 120,685	$ 90,058
Restricted cash	42,812	19,432	8,677	20,821
Pledged securities	148,996	137,236	121,767	$ 116,331
Loans held for sale	1,811,586	2,449,198
Loans held for investment, net	269,125	360,402
Derivative assets	37,364	49,786
Financial liabilities:
Derivative liabilities	6,403	5,066
Contingent consideration	125,808	28,829	$ 5,752
Warehouse notes payable	1,941,572	2,517,156
Note payable	740,174	291,593
Carrying Amount
Financial assets:
Cash and cash equivalents	305,635	321,097
Restricted cash	42,812	19,432
Pledged securities	148,996	137,236
Loans held for sale	1,811,586	2,449,198
Loans held for investment, net	269,125	360,402
Derivative assets	37,364	49,786
Total financial assets	2,615,518	3,337,151
Financial liabilities:
Derivative liabilities	6,403	5,066
Contingent consideration	125,808	28,829
Secured borrowings		73,314
Warehouse notes payable	1,941,572	2,517,156
Note payable	740,174	291,593
Total financial liabilities	2,813,957	2,915,958
Fair Value
Financial assets:
Cash and cash equivalents	305,635	321,097
Restricted cash	42,812	19,432
Pledged securities	148,996	137,236
Loans held for sale	1,811,586	2,449,198
Loans held for investment, net	270,826	362,586
Derivative assets	37,364	49,786
Total financial assets	2,617,219	3,339,335
Financial liabilities:
Derivative liabilities	6,403	5,066
Contingent consideration	125,808	28,829
Secured borrowings		73,314
Warehouse notes payable	1,942,448	2,518,101
Note payable	745,175	294,773
Total financial liabilities	$ 2,819,834	$ 2,920,083