Revenues - Revenues By Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	$ 115,810	$ 101,215
United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	94,333	77,950
Other countries
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	$ 21,477	$ 23,265
Revenue from Contract with Customer | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	100.00%	100.00%
Revenue from Contract with Customer | Geographic Concentration Risk | United States
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	81.00%	77.00%
Revenue from Contract with Customer | Geographic Concentration Risk | Other countries
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	19.00%	23.00%