Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Carrying value and estimated fair value of convertible notes and long-term debt
Convertible senior notes, net of discount			$ 99,738
Capital lease obligations	1,890		1,642
Capital lease obligations, fair value	1,869		1,611
Convertible senior secured notes (2010 Notes) [Member]
Carrying value and estimated fair value of convertible notes and long-term debt
Debt instrument, fair value		[1]	37,561	[1]
Convertible senior unsecured notes (2008 Notes) [Member]
Carrying value and estimated fair value of convertible notes and long-term debt
Convertible senior notes, net of discount	56,263	[1]	69,880	[1]
Carrying Value [Member]
Carrying value and estimated fair value of convertible notes and long-term debt
Capital lease obligations	1,890		1,642
Carrying Value [Member] | Convertible senior secured notes (2010 Notes) [Member]
Carrying value and estimated fair value of convertible notes and long-term debt
Convertible senior notes, net of discount		[1]	34,134	[1]
Carrying Value [Member] | Convertible senior unsecured notes (2008 Notes) [Member]
Carrying value and estimated fair value of convertible notes and long-term debt
Convertible senior notes, net of discount	$ 54,062	[1]	$ 65,604	[1]

[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