MARKETABLE SECURITIES (Tables)

12 Months Ended

Dec. 31, 2016

Cash and Cash Equivalents [Abstract]

Summary of Available-for-Sale Marketable Securities

The following is a summary of available-for-sale marketable securities at December 31, 2015 and 2016:


	As at December 31, 2016
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Available-for-sale—matures within one year:
Corporate bonds	$	9,456	$	4	$	(15	)	$	9,445

		9,456		4		(15	)		9,445
Available-for-sale—matures after one year through five years:
Government bonds		501		—		(4	)		497
Corporate bonds		52,490		3		(567	)		51,926

		52,991		3		(571	)		52,423
Total	$	62,447	$	7	$	(586	)	$	61,868


	As at December 31, 2015
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Available-for-sale—matures within one year:
Certificate of deposits	$	1	$	—	$	—		$	1
Corporate bonds		9,257		1		(50	)		9,208

		9,258		1		(50	)		9,209
Available-for-sale—matures after one year through three years: :
Corporate bonds		39,501		—		(444	)		39,057

		39,501		—		(444	)		39,057
Total	$	48,759	$	1	$	(494	)	$	48,266

Summary of Gross Unrealized Losses and Fair Values on Investments

The following table presents gross unrealized losses and fair values for those investments that were in an unrealized loss position as of December 31, 2015 and 2016, and the length of time that those investments have been in a continuous loss position:


	Less than 12 months					12 months or greater
	Fair Value		Gross unrealized loss			Fair Value		Gross unrealized loss
As of December 31, 2016	$	48,663	$	(557	)	$	4,875	$	(29	)
As of December 31, 2015	$	32,695	$	(389	)	$	14,488	$	(105	)

Summary of Gross Realized Gain and Loss from Sale of Available-for-Sale Marketable Securities

The following table presents gross realized gains and losses from sale of available-for-sale marketable securities:


	Year ended December 31,
	2014			2015			2016
Gross realized gains from sale of available-for-sale marketable securities	$	99		$	4		$	24
Gross realized losses from sale of available-for-sale marketable securities	$	(93	)	$	(82	)	$	(33	)