SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash Flows (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents
Cash and cash equivalents	$ 193,695	$ 191,218	$ 50,745	$ 118,756
Restricted cash	16,991	6,677	9,313	9,861
Pledged cash and cash equivalents	74,445	88,785	84,808	82,742
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	$ 285,131	$ 286,680	$ 144,866	$ 211,359