Business Combinations (Narrative) (Details) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2015 USD ($)	[1]	Jun. 30, 2015 USD ($)	[1]	Mar. 31, 2015 USD ($)	[1]	Dec. 31, 2014 USD ($)		Sep. 30, 2015 USD ($) $ / shares		Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($) Acquisitions
Business Acquisition [Line Items]
Acquisitions, less cash acquired									$ 34.5		$ 0.0	$ 224.9
Gain on previously held equity interest	$ 0.0		$ 0.0		$ 0.0		$ 17.9	[1]	17.9	[1]	$ 0.0	0.0
Production Joint Venture [Member]
Business Acquisition [Line Items]
Acquisitions, less cash acquired							$ 22.6
Percent ownership before acquisition							50.00%
Percent ownership after acquisition							100.00%
Gain on previously held equity interest									17.9
Gain on previously held equity interest, after tax									$ 11.2
Gain on previously held equity interest, per share | $ / shares									$ 0.05
2013 Business Combinations
Business Acquisition [Line Items]
Purchase price of acquired entity												$ 233.0
2013 Business Combinations | Purchase from other shareholder [Member]
Business Acquisition [Line Items]
Number of businesses acquired | Acquisitions												3

[1] For additional information, see Note 6, Business Combinations.