Amount of amortization expense attributable to debt issuance costs.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Gross amount of debt extinguished.

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The amount of cash paid for interest during the period.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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Debt - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Debt Instrument [Line Items]
Cash payments paid for interest			$ 43.1	$ 42.9
Amortization of treasury lock settlements		$ 1.4	2.8	2.8
Amortization of deferred financing costs	$ 0.5	$ 0.4	0.9	$ 0.9
Deferred finance costs, net	11.5		11.5
Unsecured Debt \| Seven-Year Term Loan, due October 2020
Debt Instrument [Line Items]
Repayment of debt			$ 3.3
Debt Instrument, Term			7 years
Senior Notes \| Fixed-Rate Senior Notes
Debt Instrument [Line Items]
Book value of fixed rate debt	1,650.0		$ 1,650.0
Long-term debt (fixed-rate debt), fair value	1,773.0		1,773.0
Term Loan \| Variable-Rate Term Loans
Debt Instrument [Line Items]
Book value of variable rate debt	$ 658.8		$ 658.8
Adjustments for ASU 2015-03 \| Other Long-term Assets
Debt Instrument [Line Items]
Deferred finance costs, net					$ (12.3)