Acquisitions Acquisitions Narrative (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Business Acquisition [Line Items]
Number of Businesses Acquired	4	8
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	$ 90.0	$ 66.0
IAN
Business Acquisition [Line Items]
Number of Businesses Acquired	2	7
CMG
Business Acquisition [Line Items]
Number of Businesses Acquired	2	1