Business Combinations Business Combinations - Table 2 (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill, Acquired During Period		$ 806.1	$ 593.1	$ 13.7
Payments to Acquire Businesses, Net of Cash Acquired		$ 985.1	$ 694.8	$ 28.9
Reliant [Member]
Business Acquisition [Line Items]
Fair value of assets acquired	$ 316.6
Goodwill, Acquired During Period	642.6
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	(230.0)
Fair value of noncontrolling interest owned by joint venture partner	(0.4)
Payments to Acquire Businesses, Net of Cash Acquired	$ 728.8