SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Statement of Cash Flows (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Cash and cash equivalents	$ 50,745	$ 118,756	$ 98,224	$ 136,988
Restricted cash	9,313	9,861	10,006	5,306
Pledged securities, at fair value	86,900	84,850	75,225	72,190
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	$ 146,958	$ 213,467	$ 183,455	$ 214,484