Debt (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Convertible Notes
Convertible subordinated notes	$ 9,159	$ 9,033
Convertible senior notes	328,354	322,043
Carrying Amount
Convertible Notes
Long-term debt, noncurrent	337,513	331,076
Fair Value
Convertible Notes
Long-term debt, noncurrent	1,098,699	811,613
Pfizer convertible subordinated note due 2014 \| Carrying Amount
Convertible Notes
Convertible subordinated notes	9,159	9,033
Pfizer convertible subordinated note due 2014 \| Fair Value
Convertible Notes
Convertible subordinated notes	18,784	13,573
4.75% convertible senior notes due 2015
Convertible Notes
Interest rate of debt (as a percent)	4.75%	4.75%
4.75% convertible senior notes due 2015 \| Carrying Amount
Convertible Notes
Convertible senior notes	328,354	322,043
4.75% convertible senior notes due 2015 \| Fair Value
Convertible Notes
Convertible senior notes	$ 1,079,915	$ 798,040

Carrying amount of long-term convertible debt as of the balance sheet date, net of the amount due in the next twelve months or greater than the normal operating cycle, if longer. The debt is convertible into another form of financial instrument, typically the entity's common stock.

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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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- Definition

The portion of the carrying value of convertible subordinated debt as of the balance sheet date that is scheduled to be repaid after one year or beyond the normal operating cycle if longer. This form of debt can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder, and places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

+ References

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- Definition

Interest rate stated in the contractual debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: 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(a)(1))

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

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

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