Acquisitions, Intangible Assets and Goodwill - Schedule of Preliminarily Allocated Purchase Price of Assets and Liability (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Apr. 01, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 409,772		$ 336,861
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