New Financial Accounting Pronouncements - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash Reported within Condensed Consolidated Statements of Cash Flows (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cash and cash equivalents	$ 33,089	$ 29,902
Total cash, cash equivalents and restricted cash	34,022	$ 30,659	$ 46,839	$ 48,006
ASU 2016-18 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cash and cash equivalents	33,089		44,999
Restricted cash	933		1,272
Restricted cash included within deferred charges and other assets			568
Total cash, cash equivalents and restricted cash	$ 34,022		$ 46,839