Debt Schedule of Debt Instruments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Total principal amount of debt	$ 2,221.8us-gaap_DebtInstrumentCarryingAmount	$ 3,001.8us-gaap_DebtInstrumentCarryingAmount
Less unamortized discount	(3.7)	(4.3)
Total long-term debt outstanding	2,218.1us-gaap_LongTermDebt	2,997.5us-gaap_LongTermDebt
Revolving Credit Facility due 2016 [Member]
Debt Disclosure [Abstract]
Long-term Debt, Weighted Average Interest Rate	2.23%	2.22%
Debt Instrument [Line Items]
Total principal amount of debt	0	480.0
Term Loan due 2017 [Member]
Debt Disclosure [Abstract]
Long-term Debt, Weighted Average Interest Rate	2.28%	2.22%
Debt Instrument [Line Items]
Total principal amount of debt	0	300.0
6.05% Senior Notes due 2016 [Member]
Debt Instrument [Line Items]
Total principal amount of debt	176.8	176.8
6.80% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Total principal amount of debt	134.0	134.0
6.80% Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Total principal amount of debt	136.0	136.0
6.875% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Total principal amount of debt	625.0	625.0
5.375% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Total principal amount of debt	500.0	500.0
5.25% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Total principal amount of debt	$ 650.0	$ 650.0

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Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Weighted average interest rate of long-term debt outstanding.

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No definition available.

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