Description of Business - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Description Of Business [Abstract]
Cash and cash equivalents	$ 28,433	$ 43,471	[1]

[1] The condensed consolidated balance sheet as of December 31, 2017 has been derived from the audited consolidated financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017.