Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Financial Assets by Major Security Type and Contingent Consideration Liability Measured at Fair Value on Recurring Basis

The following table represents the fair value hierarchy for our financial assets (cash equivalents and marketable securities) by major security type and contingent consideration liability measured at fair value on a recurring basis as of December 31, 2015 and 2014 (in thousands):

December 31, 2015	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	6,806	$	—	$	—	$	6,806
Corporate debt securities		—		—		—		—
Total assets	$	6,806	$	—	$	—	$	6,806
Liabilities
Contingent consideration liability	$	—	$	—	$	2,800	$	2,800
Total liabilities	$	—	$	—	$	2,800	$	2,800

December 31, 2014	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	12,674	$	—	$	—	$	12,674
Corporate debt securities		—		24,617		—		24,617
Total assets	$	12,674	$	24,617	$	—	$	37,291
Liabilities
Contingent consideration liability	$	—	$	—	$	30,800	$	30,800
Total liabilities	$	—	$	—	$	30,800	$	30,800

Fair Value Measurement of Contingent Consideration Liability

The following table represents a reconciliation of the change in the fair value measurement of the contingent consideration liability for the fiscal years ended December 31, 2015 and 2014 (in thousands):

	December 31,
	2015			2014
	(In thousands)
Beginning balance	$	30,800		$	39,200
Payments made		(868	)		(251	)
Adjustments to fair value measurement		(27,132	)		(8,149	)
Ending balance	$	2,800		$	30,800

Schedule of Inventory

Our inventory as of December 31, 2015 and 2014, net of reserves, in thousands, is summarized as follows:

	December 31,
	2015		2014
Raw materials	$	—	$	3,677
Work in process		—		—
Finished goods		—		52
Total inventory	$	—	$	3,729

Share-based Compensation Grant Date Fair Value

During the fiscal years ended December 31, 2015, 2014 and 2013, the weighted average fair value per share of the employee stock options, restricted stock units and stock purchase rights granted were:

	2015		2014		2013
Stock Options	$	0.80	$	2.83	$	3.46
Restricted Stock Units		—		—		4.67
Stock Purchase Rights		0.67		1.32		1.76

Share-based Compensation Assumptions

During the fiscal years ended December 31, 2015, 2014 and 2013, we calculated the estimated grant date fair value of stock options and stock purchase rights using the following assumptions:

	2015		2014		2013
Stock Option Plans
Weighted-average expected term	5.0 Years		5.0 Years		5.0 Years
Expected volatility		86%		83%		99%
Risk-free interest rate		1.60%		1.66%		0.86%
Dividend yield		0%		0%		0%

Employee Stock Purchase Plan
Weighted-average expected term	0.5 Years		0.5 Years		0.5 Years
Expected volatility		87%		61%		80%
Risk-free interest rate		0.19%		0.86%		0.70%
Dividend yield		0%		0%		0%