Recent Accounting Pronouncements Effects of Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ 9.4	$ 12.2
Long-term Debt, Excluding Current Maturities	$ (3,240.3)	(3,150.6)
Adjustments for New Accounting Pronouncement [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		3.2
Long-term Debt, Excluding Current Maturities		(3,141.6)
Adjustments for New Accounting Pronouncement [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		9.0
Long-term Debt, Excluding Current Maturities		$ (9.0)