Revenue from Contracts with Customers - Disaggregation of Revenue (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]
Total revenue	$ 78,959	$ 58,441	$ 152,144	$ 112,956
United States [Member]
Disaggregation of Revenue [Line Items]
Total revenue	64,106	47,773	124,046	91,983
All other [Member]
Disaggregation of Revenue [Line Items]
Total revenue	14,853	10,668	28,098	20,973
Subscription Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenue	52,309	31,361	99,278	60,130
Term And Perpetual License [Member]
Disaggregation of Revenue [Line Items]
Total revenue	10,315	6,697	18,991	12,257
Maintenance and Support [Member]
Disaggregation of Revenue [Line Items]
Total revenue	9,372	10,610	18,929	21,363
Professional Services [Member]
Disaggregation of Revenue [Line Items]
Total revenue	6,380	8,788	13,720	17,271
Other [Member]
Disaggregation of Revenue [Line Items]
Total revenue	$ 583	$ 985	$ 1,226	$ 1,935