MARKETABLE SECURITIES (Tables)

12 Months Ended

Dec. 31, 2014

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, 2013 and 2014:

	As at December 31, 2014
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Available-for-sale – matures within one year:
Corporate bonds	$	5,443	$	—	$	(46	)	$	5,397
		5,443		—		(46	)		5,397
Available-for-sale – matures after one year through three years:
Certificate of deposits		1,975		—		—			1,975
Corporate bonds		40,835		9		(383	)		40,461
		42,810		9		(383	)		42,436
Total	$	48,253	$	9	$	(429	)	$	47,833
	As at December 31, 2013
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Available-for-sale – matures within one year:
Corporate bonds	$	2,852	$	6	$	(3	)	$	2,855
Available-for-sale – matures after one year through three years:
Corporate bonds		65,702		134		(227	)		65,609
Total	$	68,554	$	140	$	(230	)	$	68,464

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, 2013 and 2014, 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, 2014	$	34,152	$	(313	)	$	9,469	$	(116	)
As of December 31, 2013	$	28,535	$	(208	)	$	4,278	$	(22	)

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

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

	Year ended December 31,
	2012			2013			2014
Gross realized gain from sale of available-for-sale marketable securities	$	301		$	400		$	99
Gross realized loss from sale of available-for-sale marketable securities	$	(117	)	$	(21	)	$	(93	)