Convertible Notes, Long - Term Debt and Credit Facility (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Components of convertible notes and long-term debt
Less discount on notes	$ (1,438)		$ (6,766)
Convertible senior notes, net of discount			99,738
Less amount reported as current	(54,062)
Convertible senior notes, less current portion			99,738
Capital lease obligations	1,890		1,642
Less current portion of long-term debt	(1,002)		(767)
Long-term debt, less current portion	888		875
Convertible senior unsecured notes (2008 Notes) [Member]
Components of convertible notes and long-term debt
Convertible senior unsecured notes	55,500		70,500
Convertible senior notes, net of discount	56,263	[1]	69,880	[1]
Convertible senior secured notes (2010 Notes) [Member]
Components of convertible notes and long-term debt
Convertible senior unsecured notes			$ 36,004

[1] The carrying value of the convertible senior notes and senior secured notes is representative of the bifurcated debt components only, while the fair value is based on the market value of the respective notes, which includes the convertible equity component