Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value Measurements [Abstract]

Liabilities measured at fair value on a recurring basis, fair value hierarchy of valuation techniques

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
At September 30, 2012:
None	$	—	$	—	$	—	$	—
At December 31, 2011:
Common stock warrants (1)	$	—	$	—	$	16,622	$	16,622

(1) The fair value of the common stock warrants was estimated using a Black-Scholes option pricing model. See Note 12 for additional information regarding warrants.

Changes in warrant liability

	Nine Months Ended September 30, 2012			Year Ended December 31, 2011
Balance, beginning of period	$	16,622		$	26,193
Fair value adjustments, net		(2,649	)		(9,571	)
Reclassification to additional paid-in capital		(13,973	)		—
Net transfers in/(out)		—			—
Balance, end of period	$	—		$	16,622

Carrying value and estimated fair value of convertible notes and long-term debt

	September 30, 2012				December 31, 2011
	Carrying Value		Fair Value		Carrying Value		Fair Value
Convertible senior notes (2008 Notes) (1)	$	54,062	$	56,263	$	65,604	$	69,880
Convertible senior secured notes (2010 Notes) (1)		—		—		34,134		37,561
Capital lease obligations		1,890		1,869		1,642		1,611

(1) The carrying value of the 2008 and 2010 Notes represents the discounted debt component only, while the fair value of the Notes is based on the market value of the respective notes, including convertible equity features.