FINANCIAL INSTRUMENTS (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of carrying amount and fair value of the long-term debt

The carrying amount and fair value of the Notes are as follows (in thousands):

Financial Liabilities Carried at Historical Cost	Carrying Value		Fair Value Measurements Using
March 31, 2016			Level 1		Level 2		Level 3
3.25% convertible senior notes *	$	105,215	$	—	$	262,551	$	—

* The fair value of the Notes was based on the closing price of the Company’s common stock of $52.98 per share at March 31, 2016 compared to a conversion price of $24.82 per share which, if converted, would result in an approximate conversion premium of 2.5 million shares or $134.5 million of cash. The maximum conversion premium that can be due on the Notes is 4.8 million shares, which assumes no increases in the conversion rate for certain corporate events.

Schedule of short-term investments

The following summarizes the Company’s investments at March 31, 2016 and December 31, 2015 (in thousands): 

March 31, 2016	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value (Level 2)
Debt securities:
Short-term:
Asset-backed securities	$	26,164	$	6	$	(4	)	$	26,166
Commercial paper	36,650		64		—			36,714
Corporate bonds	52,098		22		(8		)	52,112
Subtotal	114,912		92		(12		)	114,992
Long-term:
Corporate bonds	13,501		—		(31		)	13,470
Total	$	128,413	$	92	$	(43	)	$	128,462

December 31, 2015	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value (Level 2)
Debt securities:
Short-term:
Asset-backed securities	$	27,484	$	—	$	(15	)	$	27,469
Commercial paper	35,191		31		—			35,222
Corporate bonds	39,319		2		(31		)	39,290
Subtotal	101,994		33		(46		)	101,981
Long-term:
Corporate bonds	13,501		—		(39		)	13,462
Total	$	115,495	$	33	$	(85	)	$	115,443