Convertible Senior Notes (Schedule Of Principal Amount Of Liability Component, Unamortized Discount And Net Carrying Amount Of Convertible Senior Notes) (Details) (USD $)	Sep. 30, 2011	Dec. 31, 2010
Convertible Senior Notes [Line Items]
Total convertible senior notes, net	$ 488,964,000	$ 668,697,000
Less current portion		(200,000,000)
Non-current portion	488,964,000	468,697,000
2004 Notes - Due April 15, 2011
Convertible Senior Notes [Line Items]
Principal amount		200,000,000
2007 Notes - Due June 15, 2014
Convertible Senior Notes [Line Items]
Principal amount	575,000,000	575,000,000
Unamortized debt discount	(86,036,000)	(106,303,000)
Net carrying amount	$ 488,964,000	$ 468,697,000