Summary of Significant Accounting Policies - Schedule of Revenue Disaggregated by Type of Revenue and Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenues	$ 251,414	$ 213,055	$ 742,063	$ 627,792
Americas (principally the U.S.)
Disaggregation Of Revenue [Line Items]
Total revenues	218,694	180,489	643,814	530,609
Europe, Middle East, and Africa
Disaggregation Of Revenue [Line Items]
Total revenues	23,284	21,723	70,516	64,135
Asia Pacific
Disaggregation Of Revenue [Line Items]
Total revenues	9,436	10,843	27,733	33,048
Cloud and Related Solutions
Disaggregation Of Revenue [Line Items]
Total revenues	224,347	186,473	666,120	551,390
Software and Services
Disaggregation Of Revenue [Line Items]
Total revenues	14,406	14,283	39,607	39,573
Maintenance
Disaggregation Of Revenue [Line Items]
Total revenues	$ 12,661	$ 12,299	$ 36,336	$ 36,829