Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Short-term investments:
Available-for-sale securities	$ 51,304	$ 3,037
Trading securities held in Non - Qualified Deferred Compensation Plan, or NQDC	24,009	24,058
2015 Notes Hedges	219,199	215,113
Foreign currency exchange contracts	942	200
Total Assets	818,200	726,510
Liabilities
Acquisition-related contingent consideration	3,997	3,911
2015 Notes Embedded Conversion Derivative	219,199	215,113
Total Liabilities	223,196	219,024
Corporate debt securities [Member]
Short-term investments:
Available-for-sale securities	26,084
United States government agency securities [Member]
Short-term investments:
Available-for-sale securities	2,208
United States Treasury securities [Member]
Short-term investments:
Available-for-sale securities	17,255
Bank certificates of deposit [Member]
Assets
Cash equivalents	1,000
Short-term investments:
Available-for-sale securities	1,995
Commercial paper [Member]
Assets
Cash equivalents	1,200
Short-term investments:
Available-for-sale securities	1,498
Marketable equity securities [Member]
Short-term investments:
Available-for-sale securities	2,264	3,037
Money market funds [Member]
Assets
Cash equivalents	520,546	484,102
Fair Value Measurements, Level 1 [Member]
Short-term investments:
Trading securities held in Non - Qualified Deferred Compensation Plan, or NQDC	24,009	24,058
Total Assets	566,282	511,197
Fair Value Measurements, Level 1 [Member] \| United States government agency securities [Member]
Short-term investments:
Available-for-sale securities	2,208
Fair Value Measurements, Level 1 [Member] \| United States Treasury securities [Member]
Short-term investments:
Available-for-sale securities	17,255
Fair Value Measurements, Level 1 [Member] \| Marketable equity securities [Member]
Short-term investments:
Available-for-sale securities	2,264	3,037
Fair Value Measurements, Level 1 [Member] \| Money market funds [Member]
Assets
Cash equivalents	520,546	484,102
Fair Value Measurements, Level 2 [Member]
Short-term investments:
2015 Notes Hedges	219,199	215,113
Foreign currency exchange contracts	942	200
Total Assets	251,918	215,313
Liabilities
2015 Notes Embedded Conversion Derivative	219,199	215,113
Total Liabilities	219,199	215,113
Fair Value Measurements, Level 2 [Member] \| Corporate debt securities [Member]
Short-term investments:
Available-for-sale securities	26,084
Fair Value Measurements, Level 2 [Member] \| Bank certificates of deposit [Member]
Assets
Cash equivalents	1,000
Short-term investments:
Available-for-sale securities	1,995
Fair Value Measurements, Level 2 [Member] \| Commercial paper [Member]
Assets
Cash equivalents	1,200
Short-term investments:
Available-for-sale securities	1,498
Fair Value Measurements, Level 3 [Member]
Liabilities
Acquisition-related contingent consideration	3,997	3,911
Total Liabilities	$ 3,997	$ 3,911

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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