Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2012

Fair Value Measurements [Abstract]

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

Liabilities required to be measured at fair value on a recurring basis, including identification of the fair value hierarchy of the valuation techniques used by the Company to determine these fair values, are as follows (in thousands):

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
At June 30, 2012:
Common stock warrants	$	—	$	—	$	—	$	—
At December 31, 2011:
Common stock warrants (1)	$	—	$	—	$	16,622	$	16,622

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

Changes in warrant liability

	Six Months Ended June 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

The carrying value and estimated fair value of the Company’s convertible notes and long-term debt are as follows (in thousands):

	June 30, 2012				December 31, 2011
	Carrying Value		Fair Value		Carrying Value		Fair Value
Convertible senior notes (2008 Notes) (1)	$	53,231	$	56,610	$	65,604	$	69,880
Convertible senior secured notes (2010 Notes) (1)		—		—		34,134		37,561
Capital lease obligations		1,990		1,932		1,647		1,611

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