Goodwill and Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of acquired intangible assets	$ 27,067	$ 32,057	$ 21,547
Future amortization expense, 2016	26,500
Future amortization expense, 2017	27,800
Future amortization expense, 2018	23,700
Future amortization expense, 2019	21,700
Future amortization expense, 2020	$ 17,700