Stock Options, Restricted Stock Units and Employee Stock Purchase Plan - Summary of Valuation Inputs for PSUs with Vesting Subject to Market Conditions (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk Free Rate	2.52%	0.00%
Dividend	0.00%	0.00%
Expected Term (years)	6 years 2 months 12 days	0 years
Performance Shares, Vesting Subject to Market Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSUs Issued (in Shares)	254
Risk Free Rate	2.58%
Volatility	55.10%
Dividend	0.00%
Valuation Per Share (in Dollars per share)	$ 3.73
Total Fair Value (in thousands)	$ 947
Expected Term (years)	4 years
Forfeiture Rate Assumed	8.00%