Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2017

Fair value of asset measured on a recurring basis

The fair value of the Company’s financial assets measured at fair value on a recurring basis was determined using the following inputs at March 31, 2017 (in thousands):



	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		(Level 1)		(Level 2)		(Level 3)
Assets:
Money market funds ⁽¹⁾	$	4,536	$	4,536	$	—	$	—
U.S. government securities⁽²⁾	13,227		—		13,227		—
Total	$	17,763	$	4,536	$	13,227	$	—

The fair value of the Company’s financial assets measured at fair value on a recurring basis was determined using the following inputs at December 31, 2016 (in thousands):



	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		(Level 1)		(Level 2)		(Level 3)
Assets:
Money market funds ⁽¹⁾	$	4,513	$	4,513	$	—	$	—
U.S. government securities⁽²⁾	13,233		—		13,233		—
Total	$	17,746	$	4,513	$	13,233	$	—

⁽¹⁾ Included in cash and cash equivalents in the Company’s condensed consolidated balance sheets


⁽²⁾	Represents the portfolio of available for sale securities that is included in restricted investments and short-term investments in the Company’s condensed consolidated balance sheets

Fair value of short term investment unrealized holdings and gains

As of March 31, 2017, the amortized cost basis, aggregate fair value, and gross unrealized holding gains and losses of the Company’s short-term investments by major security type were as follows (in thousands):



	Amortized Cost		Aggregate Fair Value		Unrealized Holding Gains		Unrealized Holding Losses
U.S. government securities	$	11,978	$	11,975	$	—	$	3

The amortized cost basis, aggregate fair value and gross unrealized holding gains and losses for the Company’s available-for-sale short-term investments, by major security type, were as follows as of December 31, 2016 (in thousands):



	Amortized Cost		Aggregate Fair Value		Unrealized Holding Gains		Unrealized Holding Losses
U.S. government securities	$	11,984	$	11,983	$	—	$	1