Long-Term Debt and Commercial Paper (Long-Term Debt) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instruments [Abstract]
Long-term debt	$ 1,983.1	$ 2,389.4
Less: unamortized debt discounts and debt issuance costs	(12.6)	(15.7)
Less: current maturities	(44.3)	(414.5)
Long-term debt, net of current maturities	$ 1,926.2	1,959.2
Senior Notes at Six Point Seven Five Percent due 2018 [Member] \| Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Apr. 15, 2018
Senior notes	$ 0.0	400.0
Percentage interest on debt instrument	6.75%
Senior Notes at Five Point Five Percent Due 2020 [Member] \| Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Feb. 01, 2020
Senior notes	$ 350.0	350.0
Percentage interest on debt instrument	5.50%
Senior Notes at Three Point Three Five Percent Due 2021 [Member] \| Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Jan. 15, 2021
Senior notes	$ 300.0	300.0
Percentage interest on debt instrument	3.35%
Senior Notes at Three Point Five Percent Due 2024 [Member] \| Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Nov. 15, 2024
Senior notes	$ 450.0	450.0
Percentage interest on debt instrument	3.50%
Senior Notes at Four Point Five Percent Due 2025 [Member] \| Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Oct. 01, 2025
Senior notes	$ 450.0	450.0
Percentage interest on debt instrument	4.50%
Senior Notes at Three Point Eight Percent Due 2027 [Member] \| Senior Notes [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Nov. 15, 2027
Senior notes	$ 300.0	300.0
Percentage interest on debt instrument	3.80%
Revolving Credit Facility Due 2022 [Member]
Debt Instruments [Abstract]
Revolving credit facility	$ 0.0	0.0
Revolving Credit Facility Due 2022 [Member] \| Line of Credit [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Oct. 19, 2022
Capital Leases and Other Debt [Member]
Debt Instruments [Abstract]
Capital leases and other debt	$ 133.1	$ 139.4

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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Contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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Amount of long-term debt and capital leases due within one year or the normal operating cycle, if longer.

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Amount of long-term debt and capital lease obligations including current maturities.

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