Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2015

Summary of financial assets and liabilities measured on recurring basis

	September 30, 2015								December 31, 2014
	Level I		Level II		Level III		Total		Level I		Level II		Level III		Total
	(in thousands)
Financial Assets:
Money market deposits	$	183,250	$	—	$	—	$	183,250	$	—	$	—	$	—	$	—
U.S. Treasury securities		18,273		—		—		18,273		—		—		—		—
U.S. agency securities		—		8,116		—		8,116		—		—		—		—
Total financial assets	$	201,523	$	8,116	$	—	$	209,639	$	—	$	—	$	—	$	—
Current Liabilities:
Warrants	$	—	$	—	$	3,741	$	3,741	$	—	$	—	$	2,232	$	2,232
Long‑term Liabilities:
Senior secured term loan	$	—	$	—	$	21,276	$	21,276	$	—	$	—	$	20,964	$	20,964
Total financial liabilities	$	—	$	—	$	25,017	$	25,017	$	—	$	—	$	23,196	$	23,196

Summary of quantitative information about inputs and valuation methodologies

					Weighted Average
					Interest on
	Fair Value at			Significant	Discount Rate
	September 30, 2015		Valuation Methodology	Unobservable Input	(range, if applicable)
	(in thousands)				(in thousands)
Senior secured term loan	$	21,276
—Term loan			Discounted Cash Flows	Discount rate on CCC bond plus premium					17.5	%
					CCC Bond range
					(6.08%‑63.76%)
—Royalty interest			Royalty interest in future revenues	Revenues Volatility	$	189,119	-	$	431,961
									32.3	%
—Loan commitment			Discounted Cash Flows	Discount rate on CCC bond plus premium					17.5	%
					CCC Bond range
					(6.08%‑63.76%)
—Warrants	$	3,741	Black-Scholes Option Pricing Model	Volatility					50.5	%

Warrants

Rollforward of fair value determined by Level 3 inputs

	Warrants
	(in thousands)
Balance at December 31, 2014	$	2,232
Change in fair value		1,509
Balance at September 30, 2015	$	3,741

Senior Secured Term Loan

Rollforward of fair value determined by Level 3 inputs

	Term Loan
	(in thousands)
Balance at December 31, 2014	$	20,964
Change in fair value recognized in non‑operating expense		312
Balance at September 30, 2015	$	21,276