Fair Value Measurements (Details) (USD $)			9 Months Ended
	Sep. 30, 2012 Convertible senior notes due 2016	Aug. 31, 2009 Convertible senior notes due 2016	Sep. 30, 2012 Auction rate securities	Sep. 30, 2012 Fair Value, Measurements, Recurring As reflected on the balance sheet	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet	Sep. 30, 2012 Fair Value, Measurements, Recurring As reflected on the balance sheet Money market funds	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet Money market funds	Sep. 30, 2012 Fair Value, Measurements, Recurring As reflected on the balance sheet Corporate and financial institutions debt	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet Corporate and financial institutions debt	Sep. 30, 2012 Fair Value, Measurements, Recurring As reflected on the balance sheet Auction rate securities	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet Auction rate securities	Sep. 30, 2012 Fair Value, Measurements, Recurring As reflected on the balance sheet U.S. government agencies	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet U.S. government agencies	Sep. 30, 2012 Fair Value, Measurements, Recurring As reflected on the balance sheet U.S. treasury bills	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet U.S. treasury bills	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet Municipal bonds	Sep. 30, 2012 Fair Value, Measurements, Recurring As reflected on the balance sheet Foreign currency option contracts Not designated as hedges	Dec. 31, 2011 Fair Value, Measurements, Recurring As reflected on the balance sheet Foreign currency option contracts Not designated as hedges	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 Money market funds	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 Money market funds	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 1 U.S. treasury bills	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 1 U.S. treasury bills	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Corporate and financial institutions debt	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Corporate and financial institutions debt	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 U.S. government agencies	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 U.S. government agencies	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Municipal bonds	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 2 Foreign currency option contracts Not designated as hedges	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 2 Foreign currency option contracts Not designated as hedges	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3	Sep. 30, 2012 Fair Value, Measurements, Recurring Level 3 Auction rate securities	Dec. 31, 2011 Fair Value, Measurements, Recurring Level 3 Auction rate securities	Sep. 30, 2012 Fair Value, Measurements, Recurring Total fair value	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value	Sep. 30, 2012 Fair Value, Measurements, Recurring Total fair value Money market funds	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value Money market funds	Sep. 30, 2012 Fair Value, Measurements, Recurring Total fair value Corporate and financial institutions debt	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value Corporate and financial institutions debt	Sep. 30, 2012 Fair Value, Measurements, Recurring Total fair value Auction rate securities	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value Auction rate securities	Sep. 30, 2012 Fair Value, Measurements, Recurring Total fair value U.S. government agencies	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value U.S. government agencies	Sep. 30, 2012 Fair Value, Measurements, Recurring Total fair value U.S. treasury bills	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value U.S. treasury bills	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value Municipal bonds	Sep. 30, 2012 Fair Value, Measurements, Recurring Total fair value Foreign currency option contracts Not designated as hedges	Dec. 31, 2011 Fair Value, Measurements, Recurring Total fair value Foreign currency option contracts Not designated as hedges
Assets:
Total				$ 442,724,000	$ 559,360,000	$ 42,316,000	$ 30,800,000	$ 252,351,000	$ 303,799,000	$ 18,239,000	$ 22,102,000	$ 100,503,000	$ 147,445,000	$ 29,284,000	$ 40,328,000	$ 14,420,000	$ 31,000	$ 466,000	$ 71,600,000	$ 71,128,000	$ 42,316,000	$ 30,800,000	$ 29,284,000	$ 40,328,000	$ 352,885,000	$ 466,130,000	$ 252,351,000	$ 303,799,000	$ 100,503,000	$ 147,445,000	$ 14,420,000	$ 31,000	$ 466,000	$ 18,239,000	$ 22,102,000	$ 18,239,000	$ 22,102,000	$ 442,724,000	$ 559,360,000	$ 42,316,000	$ 30,800,000	$ 252,351,000	$ 303,799,000	$ 18,239,000	$ 22,102,000	$ 100,503,000	$ 147,445,000	$ 29,284,000	$ 40,328,000	$ 14,420,000	$ 31,000	$ 466,000
Liabilities:
Liability for contingent consideration, current and non-current				146,279,000	159,990,000																													146,279,000	159,990,000			146,279,000	159,990,000
Convertible senior notes due 2016 (face value $230,000)				171,395,000	162,893,000																				517,017,000	303,255,000												517,017,000	303,255,000
Total				317,674,000	322,883,000																				517,017,000	303,255,000								146,279,000	159,990,000			663,296,000	463,245,000
Face value	230,000,000	230,000,000
Discount rates used in the cash flow analysis			1.25%
Change in contingent considerations liability by 1% percentage increase or decrease in probability of occurrence of each milestone			900,000
Percent change to evaluate change in the auction rate securities valuation			1.00%
Expected holding period			5 years 3 months
Change in number of year of holding period to evaluate change in auction rate securities valuation			1 year
Change in auction rate securities valuation by 1 year increase or decrease in holding period			$ 100,000