Goodwill and Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Beginning Balance	$ 851,373
Ending Balance	870,301	$ 851,373
Strategic Marketing Services
Goodwill [Roll Forward]
Beginning Balance	851,373	744,333
Acquired goodwill	43,654	149,234
Goodwill, Purchase Accounting Adjustments	2,428	3,170
Foreign currency translation	(22,298)	(11,318)
Acquisition purchase price adjustments		27,706
Ending Balance	$ 870,301	$ 851,373