Debt Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Long-term Debt, Gross	$ 2,338,552us-gaap_DebtInstrumentCarryingAmount	$ 2,346,488us-gaap_DebtInstrumentCarryingAmount
Debt Instrument, Unamortized Discount	377,482	382,212
4.75% Senior Notes, due 2022 [Member]
Long-term Debt, Gross	400,000	400,000
Long-term Debt, Fair Value	414,000	408,000
5.00% Senior Notes, due 2024 [Member]
Long-term Debt, Gross	300,000	300,000
Long-term Debt, Fair Value	328,100	316,700
3.75% Convertible Senior Subordinated Notes, due 2025 [Member]
Long-term Debt, Gross	79,969	79,972
Long-term Debt, Fair Value	234,000	211,900
Long-term Debt	54,513	54,148
Debt Instrument, Unamortized Discount	25,456	25,824
4.00% Junior Subordinated Convertible Debentures, due 2033 [Member]
Long-term Debt, Gross	305,632	306,683
Long-term Debt, Fair Value	581,500	550,200
Long-term Debt	188,616	188,550
Debt Instrument, Unamortized Discount	117,016	118,133
3.25% Convertible Senior Debentures, Due 2035 [Member]
Long-term Debt, Gross	186,033	186,033
Long-term Debt, Fair Value	203,900	197,000
Long-term Debt	180,171	178,284
Debt Instrument, Unamortized Discount	5,862	7,749
3.50% Convertible Senior Subordianted Notes, Due 2044 [Member]
Long-term Debt, Gross	424,250	424,250
Long-term Debt, Fair Value	518,900	507,000
Long-term Debt	218,954	218,474
Debt Instrument, Unamortized Discount	$ 205,296	$ 205,776

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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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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

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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 FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20, 22

-Article 5

+ Details

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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.

+ Details

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