Summary of Significant Accounting Policies - Schedule of Revenue Disaggregated by Type of Revenue and Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenues	$ 244,793	$ 201,704
Americas (principally the U.S.)
Disaggregation Of Revenue [Line Items]
Total revenues	210,729	169,903
Europe, Middle East, and Africa
Disaggregation Of Revenue [Line Items]
Total revenues	24,626	20,434
Asia Pacific
Disaggregation Of Revenue [Line Items]
Total revenues	9,438	11,367
Cloud and Related Solutions
Disaggregation Of Revenue [Line Items]
Total revenues	219,590	177,516
Software and Services
Disaggregation Of Revenue [Line Items]
Total revenues	13,028	11,959
Maintenance
Disaggregation Of Revenue [Line Items]
Total revenues	$ 12,175	$ 12,229