Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2013

Assets and Liabilities Measured at Fair Value on Recurring Basis

Assets and liabilities measured at fair value on a recurring basis as of March 31, 2013 and December 31, 2012 are as follows:

($ in thousands)			Fair Value Measurements at Reporting Date Using
Description	Balance as of March 31, 2013		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	54,550	$	54,550	$	—	$	—
Warrant liability	$	2,174	$	—	$	2,174	$	—

($ in thousands)			Fair Value Measurements at Reporting Date Using
Description	Balance as of December 31, 2012		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	72,002	$	72,002	$	—	$	—
Warrant liability	$	12,962	$	—	$	12,962	$	—