Long-Term Obligations (Debt And Equity Components) (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010
2.75% Series A [Member]
Principal amount of convertible debentures	$ 275,000,000	$ 275,000,000
Unamortized discount	(14,253,000)	(19,273,000)
Net carrying amount	260,747,000	255,727,000
Additional paid-in capital	29,065,000	29,065,000
Remaining period that discount will be amortized, months	16
2.75% Series B [Member]
Principal amount of convertible debentures	275,000,000	275,000,000
Unamortized discount	(36,229,000)	(40,953,000)
Net carrying amount	238,771,000	234,047,000
Additional paid-in capital	$ 41,238,000	$ 41,238,000
Remaining period that discount will be amortized, months	40