INVESTMENTS (Tables)

12 Months Ended

Dec. 31, 2014

Investments, Debt and Equity Securities [Abstract]

Schedule of available-for-sale investments

Short-term investments consisted of the following (in thousands):

	December 31, 2014
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate debt securities	$	118,470	$	—	$	(147	)	$	118,323
U.S. government agency securities	24,392		4		(13		)	24,383
Total short-term investments	$	142,862	$	4	$	(160	)	$	142,706

	December 31, 2013
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Corporate debt securities	$	60,882	$	9	$	(13	)	$	60,878

Schedule of investment maturity

The cost basis and fair value of the short-term investments by contractual maturity consist of the following (in thousands):

	December 31, 2014
	Amortized Cost		Fair Value
One year or less	$	114,231	$	114,113
Over one year and less than two years	28,631		28,593
Total short-term investments	$	142,862	$	142,706

Schedule of available-for-sale investments in unrealized loss position

Investments in an unrealized loss position consisted of the following (in thousands):

	December 31, 2014					December 31, 2013
	Less Than 12 Months
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Corporate debt securities	$	105,187	$	(147	)	$	18,204	$	(13	)
U.S. government agency securities	15,773		(13		)	—		—
Total short-term investments	$	120,960	$	(160	)	$	18,204	$	(13	)