Compensation and Other Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Activity

The following table summarizes the Company’s stock option activity for the year ended December 31, 2017:

	Number of shares			Weighted Average Exercise Price PerShare
Outstanding at beginning of year		568,292		$	77.70
Granted		1,387,820			10.94
Exercised		(110,400	)		5.95
Forfeited, expired or cancelled		(223,647	)		84.40
Outstanding at end of year		1,622,065		$	24.54
Exercisable at end of year		849,279		$	32.79

Unvested RSU Activity

Unvested RSU activity for the year ended December 31, 2017 is summarized below:

				Weighted-
	Number of			Average Grant-
	Shares			Date Fair Value
Unvested balance at January 1, 2017		91,228		$	39.82
Granted		11,799			4.67
Vested		(62,405	)		37.63
Forfeited		(22,142	)		45.45
Unvested balance at December 31, 2017		18,480		$	18.00

Weighted Average Assumptions

The fair value of stock options granted during the years ended December 31, 2017, 2016, and 2015, was estimated based on the following weighted average assumptions for:

	Year Ended December 31,
	2017			2016			2015
Dividend yield		0	%		0	%		0	%
Expected volatility		100	%		101	%		84	%
Risk-free interest rate		1.90	%		1.84	%		1.40	%
Expected term	5.6 years			5.6 years			5.6 years

Stock-based Compensation Expense

The following table shows total stock-based compensation expense for stock options, RSUs and ESPP in the consolidated statements of comprehensive income (loss) (in thousands):

	Year Ended December 31,
	2017		2016		2015
Research and development	$	876	$	2,805	$	5,022
General and administrative		6,425		4,221		4,705
Restructuring		—		619	—
Total stock-based compensation expense	$	7,301	$	7,645	$	9,727