Fair Value on Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Values of Financial Assets and Liabilities

The fair values of the Company’s financial assets and liabilities were determined using the following inputs at December 31, 2016 (in thousands):

	Balance sheet			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	classification	Total		(Level 1)		(Level 2)		(Level 3)
Money market funds	Cash and cash equivalents	$	8,991	$	8,991	$	—	$	—
United States government agency securities	Short-term investments		8,029		—		8,029		—
Corporate debt securities	Short-term investments		37,087		—		37,087		—
Marketable equity securities	Marketable equity securities		3,952		3,952		—		—
Total financial assets		$	58,059	$	12,943	$	45,116	$	—

The fair values of the Company’s financial assets and liabilities were determined using the following inputs at December 31, 2015 (in thousands):

	Balance sheet			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	classification	Total		(Level 1)		(Level 2)		(Level 3)
Money market funds	Cash and cash equivalents	$	59,302	$	59,302	$	—	$	—
Corporate debt securities	Short-term investments		25,698		—		25,698		—
Marketable equity securities	Marketable equity securities		11,163		11,163		—		—
Total financial assets		$	96,163	$	70,465	$	25,698	$	—

Reconciliation of Fair Value Measurement on Liabilities Using Significant Unobservable Inputs

A reconciliation of the beginning and ending balances for the warrant liability using significant unobservable inputs (Level 3) from December 31, 2014 to December 31, 2015, was as follows (in thousands):

Balance at December 31, 2014	$	10,485
Decrease in fair value of warrants		(3,566	)
Settlement of warrants exercised		(6,919	)
Balance at December 31, 2015	$	—