Stock-Based Compensation

3 Months Ended

Mar. 31, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

9. Stock-Based Compensation

Employee stock-based compensation expense is calculated based on the grant-date fair value of awards ultimately expected to vest, and is recorded on a straight-line basis over the vesting period of the awards. Forfeitures are estimated at the time of grant, based on historical option cancellation information, and revised in subsequent periods if actual forfeitures differ from those estimates.

The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands):

	Three months ended March 31,
	2016		2015
Research and development	$	550	$	699
General and administrative		893		1,157
Employee stock-based compensation expense		1,443		1,856
Non-employee stock-based compensation expense		10		108
Total stock-based compensation expense	$	1,453	$	1,964