Convertible Senior Notes (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011 number	Sep. 30, 2010	Sep. 30, 2011 number	Sep. 30, 2010	Dec. 31, 2010
Convertible Senior Notes [Abstract]
Notes Initial Principal Amount	$ 230,000,000		$ 230,000,000
Interest per annum on Senior Notes	2.25%		2.25%
Aggregate Principle Amount Retired	134,000,000		134,000,000
Principle amount per Note	1,000		1,000
Principle and Interest Paid	136,000,000		136,000,000
Expected life of the Notes in years	5		5
Remaining amortization period of discount (in months)	0		0
Liability Component Principal Amount	236,000		236,000
Liability Component Net Carrying Amount	236,000		236,000		128,261,000
Liability Component Unamortized Discount	0		0
Equity Component Carrying Amount	35,515,000		35,515,000
Effective interest rate of Notes			8.50%
Notes Contractual Interest Exp	755,000	769,000	2,266,000	2,321,000
Amortization of Debt Discount	2,021,000	2,006,000	6,032,000	5,713,000
Amortization of Debt issuance cost	137,000	138,000	412,000	412,000
Total	$ 2,913,000	$ 2,913,000	$ 8,710,000	$ 8,446,000