Debt Issue (Details) (6.95% Senior Notes, USD $)	9 Months Ended
Sep. 30, 2011
6.95% Senior Notes
Debt Disclosure
Amount of debt issued	$ 342,000,000
Date of debt issuance	May 2011
Call date of debt issued	May 15, 2016
Maturity date of debt issued	May 15, 2060
Debt issuance cost	$ 11,000,000
Interest rate on debt	6.95%

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The earliest date, before maturity, on which the issuer can call the outstanding debt instrument for repayment or conversion to equity, which may be presented in a variety of ways (year only, month and year, day, month and year, quarter, etc.).

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The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

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Interest rate stated in the contractual debt agreement.

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Date when the debt instrument was issued, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

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Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

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For an unclassified balance sheet, the amount as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain. Such amount is before the consideration of accumulated amortization.

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