Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 134,045	$ 114,073
Less accumulated depreciation and amortization	(74,888)	(51,342)
Property and equipment, net	59,157	62,731
Hosting equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	37,222	35,018
Capitalized internal-use software
Property Plant And Equipment [Line Items]
Property and equipment, gross	31,593	25,773
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	28,113	25,396
Computer equipment and licensed software and patents
Property Plant And Equipment [Line Items]
Property and equipment, gross	16,316	11,879
Furniture and fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,581	8,014
Construction in progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 11,220	$ 7,993