New Accounting Pronouncements - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash Reported Accompanying Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cash and cash equivalents	$ 3,493	$ 424
Restricted cash	32,551	32,985
Total cash, cash equivalents and restricted cash	36,044	$ 33,409	$ 33,382	$ 31,374
Accounting Standards Update 2016-18 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cash and cash equivalents	3,493		1,278
Restricted cash	32,551		32,104
Total cash, cash equivalents and restricted cash	$ 36,044		$ 33,382