Basis of Presentation and Summary of Significant Accounting Policies - Summary of Change in Cash Flows As Reported and As Previously Reported Prior to Adoption (Detail) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
Cash And Cash Equivalents [Line Items]
Change in restricted cash		$ 0	$ 0
Net cash provided by (used in) investing activities		(22,087)	9,941
Net increase		16,684	40,238
CASH, CASH EQUIVALENTS AND RESTRICTED CASH - Beginning of period	[1]	194,874	109,295
CASH, CASH EQUIVALENTS AND RESTRICTED CASH - End of period	[1]	$ 211,558	149,533
As previously Reported [Member]
Cash And Cash Equivalents [Line Items]
Change in restricted cash			(154)
Net cash provided by (used in) investing activities			9,787
Net increase			40,084
CASH, CASH EQUIVALENTS AND RESTRICTED CASH - Beginning of period	[1]		107,343
CASH, CASH EQUIVALENTS AND RESTRICTED CASH - End of period	[1]		$ 147,427

[1] Amounts in As Reported column include cash, cash equivalents and restricted cash as required. Amounts in the As Previously Reported column reflect only cash and cash equivalents.