Stock Incentive Plans - Schedule of Stock Options Valuation Assumptions Using a Black-Scholes Option Pricing Model (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility		54.38%
Expected volatility, minimum	56.56%		52.80%	53.52%
Expected volatility, maximum	56.64%		60.12%	54.38%
Weighted-average risk-free interest rate		1.76%
Weighted-average risk-free interest rate, minimum	2.77%		2.33%	1.76%
Weighted-average risk-free interest rate, maximum	3.00%		3.00%	2.28%
Expected term (in years)	6 years 3 months	6 years 3 months		6 years 3 months
Underlying common stock fair value		$ 2.89
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)			5 years 6 months
Underlying common stock fair value	$ 15.96		$ 6.63
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)			7 years 7 months 6 days
Underlying common stock fair value	$ 20.41		$ 20.98	$ 2.89