Reconciliation of Cash and Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents presented in the consolidated condensed balance sheets	$ 38,769	$ 39,620	$ 70,482	$ 103,172
Restricted cash	2,500
Cash, cash equivalents and restricted cash presented in the consolidated condensed statements of cash flows	$ 41,269	$ 39,620	$ 70,482	$ 103,172