Debt Convertible Debt (Details) (USD $)
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12 Months Ended | 3 Months Ended | 12 Months Ended | 0 Months Ended | 12 Months Ended | |||||||||||
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Dec. 31, 2010
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Dec. 31, 2009
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Dec. 31, 2008
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Dec. 31, 2010
Convertible obligations [Member]
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Dec. 31, 2009
Convertible obligations [Member]
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Dec. 31, 2008
Convertible obligations [Member]
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Dec. 31, 2009
2.5% Senior Convertible Notes due 2023 [Member]
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Nov. 09, 2006
2.5% Senior Convertible Notes due 2023 [Member]
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Dec. 31, 2009
2.5% Senior Convertible Notes due 2023 [Member]
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Dec. 31, 2010
2.5% Senior Convertible Notes due 2023 [Member]
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Nov. 09, 2006
Floating Rate Convertible Senior Debentures due 2033 [Member]
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Dec. 31, 2009
Floating Rate Convertible Senior Debentures due 2033 [Member]
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Dec. 31, 2010
Floating Rate Convertible Senior Debentures due 2033 [Member]
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Dec. 31, 2010
3.25% Senior Subordinated Convertible Notes Due 2024 [Member]
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Dec. 31, 2009
3.25% Senior Subordinated Convertible Notes Due 2024 [Member]
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Nov. 09, 2006
3.25% Senior Subordinated Convertible Notes Due 2024 [Member]
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Debt Issuance [Line Items] | ||||||||||||||||
Face Amount Issued | $ 300,000,000 | $ 344,400,000 | $ 330,000,000 | |||||||||||||
Debt Instrument, Interest Rate, Stated Percentage | 2.50% | 3.25% | ||||||||||||||
Debt Instrument, Description of Variable Rate Basis | annual rate of 90-day LIBOR minus 1.25% | |||||||||||||||
Conversion Price per Share | 23.73 | 29.55 | 40.20 | 40.20 | ||||||||||||
Debt Instrument Convertible, Trigger Price | 28.48 | 38.41 | 48.24 | 48.24 | ||||||||||||
Convertible Subordinated Debt, Current | 100,000,000 | |||||||||||||||
Principal Amount of Convertible Debt | 329,300,000 | 668,800,000 | ||||||||||||||
Unamortized Discount | 3,800,000 | 1,400,000 | 10,900,000 | 400,000 | 1,500,000 | 1,400,000 | 9,000,000 | |||||||||
Net Carrying Amount | 327,900,000 | 657,900,000 | ||||||||||||||
Incremental Convertible Debt Obligation (Temporary Equity) | 0 | 1,900,000 | 0 | 1,900,000 | ||||||||||||
Debt Instrument Convertible Carrying Amount Of The Equity Component | 18,100,000 | 30,700,000 | ||||||||||||||
Remaining Weighted Average Discount Amortization Period (Months) | 3 | |||||||||||||||
Contractual Coupon Interest | 10,900,000 | 18,400,000 | 25,000,000 | |||||||||||||
Amortization of Discount on Convertible Debt | 9,100,000 | 22,500,000 | 21,600,000 | 9,100,000 | 22,500,000 | 21,600,000 | ||||||||||
Interest Expense | 20,000,000 | 40,900,000 | 46,600,000 | |||||||||||||
Effective Interest Rate | 4.70% | 4.30% | 5.10% | |||||||||||||
Extinguishment Of Debt [Line Items] | ||||||||||||||||
Extinguishment Of Debt Amount | 282,300,000 | 13,000,000 | 326,000,000 | |||||||||||||
Redemption Price per $1000 of Par Value | 2,072.4743 | |||||||||||||||
Extinguishment of Debt, Total Cash Outlay | 586,600,000 | 28,000,000 | 573,000,000 | |||||||||||||
Gains (Losses) On Extinguishment Of Debt | $ (17,000,000) | $ (15,000,000) | $ (10,000,000) |