Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2016

Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis

There were no transfers between Level 1 and Level 2 of the fair value measurement hierarchy during the nine months ended September 30, 2016 and the year ended December 31, 2015. Assets and liabilities measured at fair value on a recurring basis as of September 30, 2016, were as follows (in thousands):

	September 30, 2016
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	16,906	$	—	$	—	$	16,906
Corporate debt securities		—		24,334		—		24,334
Total Assets	$	16,906	$	24,334	$	—	$	41,240
Liabilities:
Common stock warrant liability	$	—	$	—	$	35	$	35

Assets and liabilities measured at fair value on a recurring basis as of December 31, 2015, were as follows (in thousands):

	December 31, 2015
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	69,845	$	—	$	—	$	69,845
Corporate debt securities		—		325		—		325
Total assets	$	69,845	$	325	$	—	$	70,170
Liabilities:
Common stock warrant liability	$	—	$	—	$	331	$	331

Summary of Changes in the Estimated Fair Value of Warrant Liabilities

The following table sets forth a summary of the changes in the estimated fair value of the warrant liability. Changes in the fair value are recognized in the change in fair value of warrant liability line item on the consolidated statements of operations. The following balance is measured at fair value on a recurring basis using significant unobservable inputs (Level 3) (in thousands):

	Common Stock
	Warrant
	Liability
Balance at January 1, 2016	$	331
Recognized gain		(52	)
Exercise of warrant		(244	)
Balance at September 30, 2016	$	35