Goodwill and Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of acquired intangible assets	$ 26,642	$ 27,067	$ 32,057
Future amortization expense, 2017	29,200
Future amortization expense, 2018	26,400
Future amortization expense, 2019	25,000
Future amortization expense, 2020	21,100
Future amortization expense, 2021	$ 16,600