Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2013

Stock-Based Compensation [Abstract]

Stock-based compensation expense

The following table shows total stock-based compensation expense included in the condensed consolidated statement of operations for the three month and six months ended June 30, 2013 and 2012 (in thousands):

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Costs and expenses:
Research and development	$	723	$	646	$	1,408	$	1,421
General and administrative		655		578		1,299		1,186
Total stock-based compensation expense	$	1,378	$	1,224	$	2,707	$	2,607