Goodwill and Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of acquired intangible assets	$ 9,648	$ 8,294	$ 19,247	$ 16,725
Future amortization expense to be recognized in remainder of 2019	19,300		19,300
Future amortization expense 2020	36,900		36,900
Future amortization expense 2021	32,000		32,000
Future amortization expense 2022	26,200		26,200
Future amortization expense 2023	$ 20,300		$ 20,300