Description of Operations and Summary of Significant Accounting Policies - Summary of Select Unaudited Condensed Consolidated Balance Sheet Reflect Adoption of Accounting Standards (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Deferred costs	$ 13,705	$ 11,898
Deferred costs, net of current portion	18,155	17,182
Liabilities and Stockholders’ Equity
Accumulated deficit	$ (210,261)	(196,865)
ASU 2014-09 | As Previously Reported
Liabilities and Stockholders’ Equity
Accumulated deficit		(225,945)
ASU 2014-09 | Adjustments
Assets
Deferred costs		11,898
Deferred costs, net of current portion		17,182
Liabilities and Stockholders’ Equity
Accumulated deficit		$ 29,080