Acquisitions, Intangible Assets and Goodwill - Schedule of Preliminarily Allocated Purchase Price of Assets and Liability (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 03, 2019	Apr. 01, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 461,110			$ 336,861
GetFeedback, Inc
Business Acquisition [Line Items]
Cash and cash equivalents		$ 678
Accounts receivable, net		1,303
Property and equipment, net		228
Operating lease right-of-use assets		3,053
Intangible assets		17,700
Goodwill		53,904
Accrued compensation		(425)
Deferred revenue		(3,866)
Operating lease liabilities		(3,053)
Deferred tax liabilities		(1,123)
Other assets and liabilities, net		(144)
Total purchase price		$ 68,255
Usabilla Holding B.V.
Business Acquisition [Line Items]
Cash and cash equivalents			$ 1,058
Accounts receivable, net			1,876
Property and equipment, net			770
Operating lease right-of-use assets			2,268
Intangible assets			15,136
Goodwill			72,077
Accrued compensation			(1,226)
Deferred revenue			(4,541)
Operating lease liabilities			(2,268)
Deferred tax liabilities			(2,323)
Other assets and liabilities, net			1,461
Total purchase price			$ 84,288