Goodwill and Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of acquired intangible assets	$ 9,624	$ 8,294	$ 28,871	$ 25,019
Future amortization expense to be recognized in remainder of 2019	9,600		9,600
Future amortization expense 2020	36,900		36,900
Future amortization expense 2021	31,900		31,900
Future amortization expense 2022	26,200		26,200
Future amortization expense 2023	$ 20,300		$ 20,300