Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2012

Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents information about the Company’s assets and liabilities as of March 31, 2012 and December 31, 2011 that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value:

	March 31, 2012
In thousands	Total		Level 1		Level 2		Level 3
Marketable securities	$	89,532	$	—	$	89,532	$	—

	December 31, 2011
In thousands	Total		Level 1		Level 2		Level 3
Warrant liability	$	58,639	$	—	$	58,639	$	—

Changes in Fair Value of Warrant Liability

The changes in the fair value of the warrant liability for the three-month periods ended March 31, 2012 and 2011 were as follows:

In thousands	Three Months Ended March 31,
	2012			2011
Balance at beginning of period	$	58,639		$	28,815
Exercise of warrants		(74,563	)		(14,863	)
Revaluation of warrant liability		15,924			18,572
Balance at end of period	$	—		$	32,524