Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2012

Summary of Financial Assets and Liabilities Measured at Fair Market Value on Recurring Basis

Financial assets and liabilities measured at fair market value on a recurring basis as of June 30, 2012 and December 31, 2011 are summarized below (in thousands):

	Fair Value at June 30, 2012						Fair Value at December 31, 2011
Assets	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
Corporate debt and auction rate securities	$	—	$	11,202	$	—	$	—	$	4,205	$	—
Liabilities
Warrant liability	$	—	$	—	$	368	$	—	$	—	$	368

Summarized Activity of Level 3 Inputs Measured on Recurring Basis

The following table summarizes the activity of Level 3 inputs measured on a recurring basis as of June 30, 2012 (in thousands):

	Fair Value Measurements of Warrants Using Significant Unobservable Inputs  (Level 3)
Balance at December 31, 2011	$	368
Change in fair value of Warrant liability		―
Balance at June 30, 2012	$	368

Short-Term Investments Classified as Available-For-Sale

Short-term investments classified as available-for-sale as of June 30, 2012 and December 31, 2011 were comprised of (in thousands):

	June 30, 2012								December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Auction rate securities	$	3,373	$	933	$	—	$	4,306	$	3,373	$	832	$	—	$	4,205
Corporate debt securities		6,889		7		—		6,896		—		—		—		—
Total	$	10,262	$	940	$	—	$	11,202	$	3,373	$	832	$	—	$	4,205