Goodwill and Acquired Intangible Assets, Net - Amortization Expense Related to Acquired Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	$ 10,815	$ 23,168	$ 10,243
Cost of net revenue
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	434	11,834	5,083
Sales, marketing and support
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	10,381	10,236	4,570
General and administrative
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	$ 0	$ 1,098	$ 590