Financial instruments (Tables)

9 Months Ended

Sep. 30, 2017

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


(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
September 30, 2017
Short-term investments:
U.S. treasury securities	$	72,693	$	—	$	(103	)	$	72,590

Contractual maturities:
Due within one year	$	72,693						$	72,590
December 31, 2016

	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Short-term investments:
U.S. treasury securities	$	70,819	$	—	$	(61	)	$	70,758

Long-term investments:
U.S. treasury securities	$	50,155	$	—	$	(109	)	$	50,046

Contractual maturities:
Due within one year	$	70,819						$	70,758
Due after one year through two years		50,155							50,046

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


(in thousands)	Period of continuous unrealized loss
	12 months or less					Greater than 12 months
	Fair value		Gross unrealized losses			Fair value		Gross unrealized losses
September 30, 2017
U.S. treasury securities	$	61,527	$	(99	)	$	11,063	$	(4	)
December 31, 2016
U.S. treasury securities	$	120,804	$	(170	)		N/A		N/A

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


(in thousands)	QUOTED PRICES IN ACTIVE MARKETS FOR IDENTICAL ASSETS (LEVEL 1)		OTHER OBSERVABLE INPUTS (LEVEL 2)		SIGNIFICANT UN-OBSERVABLE INPUTS (LEVEL 3)		TOTAL
BALANCES – September 30, 2017
Short-term investments – U.S. treasury securities	$	72,590	$	—	$	—	$	72,590

	$	72,590	$	—	$	—	$	72,590

BALANCES – December 31, 2016
Short-term investments – U.S. treasury securities	$	70,758	$	—	$	—	$	70,758
Long-term investments – U.S. treasury securities		50,046		—		—		50,046

	$	120,804	$	—	$	—	$	120,804