Debt (Details) (USD $)	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]
Principal payments on debt	$ 66,000,000
Cash payments for interest	10,500,000	5,900,000
Amortization of net (loss) gain on treasury lock	1,400,000	1,400,000
Amortization of financing costs	500,000	200,000
Book value of fixed rate debt	1,250,000,000
Book value of variable rate debt	1,230,000,000
Long-term debt (fixed-rate debt), fair value	$ 1,290,000,000

Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.

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-Name Accounting Standards Codification

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-Publisher SEC

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

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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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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 rate subject to change from time to time.

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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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