Share-Based Payments (Tables)

3 Months Ended

Mar. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock-Based Compensation Expense

Stock-based compensation expense by award type was as follows (in thousands):

	Three Months Ended March 31,
	2016		2015
Stock options	$	435	$	637
Restricted stock	54		27
Restricted stock units	92		—
Employee stock purchase plan	5		—
	$	586	$	664

Summary of Stock Option Activity and Related Information

A summary of the stock option activity is presented below:

	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2015	1,803,574		$	6.28
Granted	916,776		0.28
Exercised	(118,110	)	0.06
Cancelled or forfeited	(181,436	)	2.85
Outstanding at March 31, 2016	2,420,804		$	4.57
Exercisable at March 31, 2016	860,693		$	5.88
Vested and expected to vest at March 31, 2016(1)	2,012,694		$	5.14

(1) Represents the number of vested options, plus the number of unvested options expected to vest.

Summary of Status and Changes of Unvested Restricted Stock

A summary of the unvested restricted stock is presented below:

	Restricted Stock		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2015	41,657		$	11.05
Granted	—		—
Vested	(6,217	)	8.88
Unvested at March 31, 2016	35,440		$	11.43

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

A summary of the restricted stock units is presented below:

	Restricted Stock Units		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2015	150,932		$	2.85
Granted	—		—
Vested	(3,334	)	4.09
Unvested at March 31, 2016	147,598		$	2.82