Convertible Notes (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Convertible Notes
Total long-term convertible notes	$ 143,875	$ 133,493
5% Convertible Senior Notes due 2014
Convertible Notes
Total principal amount of convertible notes	172,500	172,500
Unamortized discount	(28,625)	(39,007)
Total convertible notes	143,875	133,493
Total long-term convertible notes	$ 143,875	$ 133,493
Convertible notes stated interest rate (as a percent)	5.00%	5.00%	5.00%

Carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Convertible Notes Payable, excluding current portion. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

+ References

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- Definition

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.

+ References

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- Definition

Interest rate stated in the contractual debt agreement.

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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