Subsequent Events (Details) (USD $)	6 Months Ended	0 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jul. 19, 2012 Subsequent Event [Member] Issuance of Debt [Member]	Jul. 16, 2012 Subsequent Event [Member] Issuance of Debt [Member]
Subsequent Event [Line Items]
Repayments of Senior Debt	$ 0	$ 75,000,000		$ 175,000,000
Debt Instrument, Interest Rate, Stated Percentage			3.00%	6.00%
Long-term Debt, Gross			250,000,000
Proceeds from Issuance of Senior Long-term Debt			$ 244,700,000

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

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The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer).

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- Definition

The cash outflow for a long-term debt where the holder has highest claim on the entity's asset in case of bankruptcy or liquidation during the period.

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