Business Combinations - Additional Information (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($) business
Business Acquisition [Line Items]
Number of acquisitions | business			5
Total consideration, net of cash acquired		$ 0.0	$ 53.0
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Total consideration, net of cash acquired	$ 50.4
Acquisition related costs	$ 0.2		$ 1.1