Description of the Business and Basis of Presentation - Summary of Restricted Cash (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 [Abstract]
Cash and cash equivalents	$ 39,343	$ 33,178
Restricted cash, included in other current assets	1,308	819
Total cash, cash equivalents and restricted cash	$ 40,651	$ 33,997	$ 34,587	$ 69,378