Financial instruments (Tables)

12 Months Ended

Dec. 31, 2015

The Company’s short-term investments and long-term investments consist of available-for-sale securities as follows:


December 31, 2015	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Short-term investments:
U.S. treasury securities	$	33,014	$	—	$	(61	)	$	32,953
U.S. government agency securities		2,003		—		—			2,003

	$	35,017	$	—	$	(61	)	$	34,956

Long-term investments:
U.S. government agency securities	$	38,687	$	—	$	(229	)	$	38,458

Contractual maturities:
Due within one year	$	35,017						$	34,956
Due after one year through two years		38,687							38,458


December 31, 2014	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Short-term investments:
U.S. treasury securities	$	12,199	$	—	$	(5	)	$	12,194
U.S. government agency securities		11,996		1		—			11,997

	$	24,195	$	1	$	(5	)	$	24,191

Long-term investments:
U.S. government agency securities	$	2,003	$	—	$	—		$	2,003

Contractual maturities:
Due within one year	$	24,195						$	24,191
Due after one year through two years		2,003							2,003

The aggregate estimated fair value of the Company’s investments with unrealized losses are as follows:


	Period of continuous unrealized loss
	12 months or less					Greater than 12 months
December 31, 2015	Fair value		Gross unrealized losses			Fair value		Gross unrealized losses
U.S. treasury securities	$	32,953	$	(61	)		NA		NA

U.S. Government agency securities		38,458		(229	)		N/A		N/A

December 31, 2014	$	12,194	$	(5	)		NA		NA

The following tables present the fair value of our financial instruments that are measured at fair value on a recurring basis:


	QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)		OTHER OBSERVABLE INPUTS (LEVEL 2)		SIGNIFICANT UN- OBSERVABLE INPUTS (LEVEL 3)			TOTAL
BALANCES – December 31, 2015
Short-term investments – U.S. treasury securities	$	32,953		—		—		$	32,953
Short-term investments – U.S. government agency securities		2,003		—		—			2,003
Long-term investments – U.S. treasury securities		38,458		—		—			38,458
Long-term investments – U.S. government agency securities		—		—		—			—
Bank loan warrant derivative liabilities		—		—		(124	)		(124	)

	$	73,414	$	—	$	(124	)	$	73,290

BALANCES – December 31, 2014
Short-term investments – U.S. treasury securities	$	12,194		—		—		$	12,194
Short-term investments – U.S. government agency securities		11,997		—		—			11,997
Investments – U.S. treasury securities		—		—		—			—
Investments – U.S. government agency securities		2,003		—		—			2,003
Bank loan warrant derivative liabilities		—		—		(72	)		(72	)

	$	26,194	$	—	$	(72	)	$	26,122

Fair value of significant unobservable inputs (Level 3):


	BANK LOAN WARRANT DERIVATIVE LIABILITIES
BALANCES – December 31, 2014	$	72
Change in fair value of derivative liabilities		52

BALANCES – December 31, 2015	$	124