Goodwill and Acquired Intangible Assets - Schedule of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 426,121	$ 399,191
Accumulated Amortization	(259,714)	(230,843)
Net Carrying Amount	166,407	168,348
Completed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	154,091	145,091
Accumulated Amortization	(95,861)	(81,587)
Net Carrying Amount	58,230	63,504
Customer-related intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	263,410	245,710
Accumulated Amortization	(158,562)	(144,786)
Net Carrying Amount	104,848	100,924
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	730	700
Accumulated Amortization	(467)	(306)
Net Carrying Amount	263	394
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,400	7,200
Accumulated Amortization	(4,334)	(3,674)
Net Carrying Amount	3,066	3,526
Acquired license rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	490	490
Accumulated Amortization	(490)	(490)
Net Carrying Amount	$ 0	$ 0