Stockholders' Equity - Additional Information (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Feb. 28, 2017
Equity Incentive Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted stock units vested during the period	$ 7,600,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program authorized amount		$ 25,000,000
Amount remaining for future repurchases	$ 6,000,000