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Debt and Debt-Related Parties - Convertible Senior Unsecured Notes (Details) (USD $)
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1 Months Ended | 3 Months Ended | 9 Months Ended | 9 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Apr. 30, 2012
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Jun. 30, 2009
Convertible Senior Unsecured Notes [Member]
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Sep. 30, 2012
Convertible Senior Unsecured Notes [Member]
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Jun. 30, 2012
Convertible Senior Unsecured Notes [Member]
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Mar. 31, 2012
Convertible Senior Unsecured Notes [Member]
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Sep. 30, 2011
Convertible Senior Unsecured Notes [Member]
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Aug. 01, 2011
Convertible Senior Unsecured Notes [Member]
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Jan. 01, 2009
Convertible Senior Unsecured Notes [Member]
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Jul. 31, 2005
Convertible Senior Unsecured Notes [Member]
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Jun. 30, 2012
Convertible Senior Unsecured Notes [Member]
Maximum [Member]
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Sep. 30, 2012
Convertible Senior Unsecured Notes [Member]
Minimum [Member]
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Sep. 30, 2012
Convertible Senior Unsecured Notes [Member]
Current Debt Discount [Member]
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Dec. 31, 2011
Convertible Senior Unsecured Notes [Member]
Current Debt Discount [Member]
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| Debt Instrument [Line Items] | |||||||||||||
| Principal amount of debt | $ 204,600,000 | $ 325,000,000 | |||||||||||
| Debt instrument interest rate, stated percentage | 2.25% | ||||||||||||
| Debt instrument initial conversion rate, (in shares) per $1,000 principal amount | 28.2326 | ||||||||||||
| Debt instrument conversion price (US$ per share) | $ 35.42 | ||||||||||||
| Percentage of debt principal that could be redeemed (percent) | 100.00% | ||||||||||||
| Trading period of the volume-weighted average price of stock (days) | 10 days | 5 days | |||||||||||
| Volume-weighted average price of common stock (US$ per share) | $ 53.13 | ||||||||||||
| Basis spread on debt instrument variable rate (percent) | 0.50% | ||||||||||||
| Aggregate debt principal amount exchanged | 120,400,000 | ||||||||||||
| Value of cash and cash equivalents debt was exchanged for | 1,400,000 | 30,000,000 | |||||||||||
| Number of shares of common stock exchanged for debt | 4,000,000 | ||||||||||||
| Number of shares of common stock that the remaining debt principal is convertible into | 5,800,000 | ||||||||||||
| Debt reclassified to currrent liability | 190,700,000 | ||||||||||||
| Due date of Convertible Senior Unsecured Notes | 12 months | ||||||||||||
| Fair value of the embedded conversion option | 134,000,000 | ||||||||||||
| Unamortized debt discount | $ 0 | $ 9,906,000 |