Debt Debt Fair Value Disclosure (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Long-term Debt, Gross	$ 2,346,488us-gaap_DebtInstrumentCarryingAmount	$ 2,500,434us-gaap_DebtInstrumentCarryingAmount
Long-term Debt	2,346,488us-gaap_LongTermDebt
Debt Instrument, Unamortized Discount	382,212	573,082
3.75% Convertible Senior Subordinated Notes Due 2042 [Member]
Long-term Debt, Gross	0	390,000
Long-term Debt, Fair Value	0	592,800
Long-term Debt	0	225,014
Debt Instrument, Unamortized Discount	0	164,986
7.75% Senior Subordinated Notes, Due 2020 [Member]
Long-term Debt, Gross	0	400,000
Long-term Debt, Fair Value	0	435,800
3.75% Convertible Senior Subordinated Notes, due 2025 [Member]
Long-term Debt, Gross	79,972	132,408
Long-term Debt, Fair Value	211,900	306,500
Long-term Debt	54,148	87,310
Debt Instrument, Unamortized Discount	25,824	45,098
4.00% Junior Subordinated Convertible Debentures, due 2033 [Member]
Long-term Debt, Gross	306,683	307,153
Long-term Debt, Fair Value	550,200	455,900
Long-term Debt	188,550	186,136
Debt Instrument, Unamortized Discount	118,133	121,017
3.25% Convertible Senior Debentures, Due 2035 [Member]
Long-term Debt, Gross		427,500
Long-term Debt, Fair Value	197,000	457,400
Long-term Debt	178,284	393,126
Debt Instrument, Unamortized Discount	7,749	34,374
3.50% Convertible Senior Subordianted Notes, Due 2044 [Member]
Long-term Debt, Gross	424,250	424,250
Long-term Debt, Fair Value	507,000	428,500
Long-term Debt	218,474	216,643
Debt Instrument, Unamortized Discount	$ 205,776	$ 207,607

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

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-Publisher FASB

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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