Subsequent Events (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended				9 Months Ended
	Oct. 31, 2016	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2013	Jun. 30, 2009	Mar. 31, 2008	Jun. 30, 2003
Subsequent Event [Line Items]
Debt repurchase, premium paid			$ 5.8
Gain (Loss) on Extinguishment of Debt			3.9	$ (5.5)		$ 3.9	$ (5.5)
Write off of Deferred Debt Issuance Cost (Less than)					$ 2.5
Deferred loss - treasury lock agreements			1.2
Loss on extinguishment, amortization of deferred hedge gain			12.8
Six Point Five Percent Notes Due March Two Thousand Nineteen [Member]
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage									6.50%
Four Point Six Zero Percent Notes, Due March Two Thousand Twenty [Member]
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage								4.60%
Five Point Seven Five Percent Notes, Due March Two Thousand Eighteen [Member]
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage										5.75%
Write off of Deferred Debt Issuance Cost (Less than)			$ 0.9
Four Point Two Percent Notes, Due July Two Thousand Eighteen [Member]
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage											4.20%
Subsequent Event [Member] | Six Point Five Percent Notes Due March Two Thousand Nineteen [Member]
Subsequent Event [Line Items]
Debt Instrument, Repurchase Amount	$ 44.0
Subsequent Event [Member] | Four Point Six Zero Percent Notes, Due March Two Thousand Twenty [Member]
Subsequent Event [Line Items]
Debt Instrument, Repurchase Amount	40.0
Subsequent Event [Member] | Five Point Seven Five Percent Notes, Due March Two Thousand Eighteen [Member]
Subsequent Event [Line Items]
Debt Instrument, Repurchase Amount	35.2
Remaining principal amount of long-term debt, to be prepaid	106.2
Subsequent Event [Member] | Four Point Two Percent Notes, Due July Two Thousand Eighteen [Member]
Subsequent Event [Line Items]
Debt Instrument, Repurchase Amount	44.0
Remaining principal amount of long-term debt, to be prepaid	132.2
Subsequent Event [Member] | Debt repurchase [Member]
Subsequent Event [Line Items]
Debt repurchase, premium paid	6.0
Accrued interest to be paid	1.0
Gain (Loss) on Extinguishment of Debt	(1.0)
Loss on extinguishment, amortization of deferred hedge gain	6.0
Subsequent Event [Member] | Debt prepayment [Member]
Subsequent Event [Line Items]
Notes Make Whole Premium	$ 13.0
Forecast [Member] | Debt repurchase [Member]
Subsequent Event [Line Items]
Deferred loss treasury lock agreements and write-off of debt issuance costs and discount/ premium		$ 1.0
Forecast [Member] | Debt prepayment [Member]
Subsequent Event [Line Items]
Accrued interest to be paid		4.0
Gain (Loss) on Extinguishment of Debt		(3.0)
Write off of Deferred Debt Issuance Cost (Less than)		1.0
Deferred loss - treasury lock agreements		1.0
Loss on extinguishment, amortization of deferred hedge gain		$ 11.0