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Debt (Details) (USD $) Share data in Millions, unless otherwise specified	0 Months Ended			0 Months Ended
	Feb. 13, 2014	Feb. 11, 2014 Senior Notes [Member] Senior Notes Due 2024 [Member]	Mar. 31, 2014 Senior Unsecured [Member]	Apr. 15, 2014 Subsequent Event [Member] Senior Unsecured Term Loan [Member]
Long-term debt
Maximum borrowing capacity			$ 1,250,000,000	$ 250,000,000
Term				5 years
Additional borrowing capacity				100,000,000
Line of credit outstanding			400,000,000
Face amount		400,000,000
Interest rate		4.25%
Shares issued in connection with conversion	1.9
Expense recognized upon redemption	$ 18,800,000

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Line of Credit Facility, Maximum Borrowing Capacity Additional Amount

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- Definition

Face (par) amount of debt instrument at time of issuance.

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

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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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Gross amount of debt extinguished.

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Amount borrowed under the credit facility as of the balance sheet date.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Number of shares issued during the period as a result of the conversion of convertible securities.

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