Revenues - Revenues By Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	$ 112,362	$ 99,226	$ 228,172	$ 200,441
United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	93,594	78,731	187,927	156,681
Other countries
Disaggregation of Revenue [Line Items]
Revenue from contract with customers	$ 18,768	$ 20,495	$ 40,245	$ 43,760
Revenue from Contract with Customer | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Revenue from Contract with Customer | Geographic Concentration Risk | United States
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	83.00%	79.00%	82.00%	78.00%
Revenue from Contract with Customer | Geographic Concentration Risk | Other countries
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	17.00%	21.00%	18.00%	22.00%