INVESTMENTS (Tables)

9 Months Ended

Sep. 30, 2016

Investments Schedule [Abstract]

Investments

Investments consist of the following (in thousands):

	September 30, 2016		December 31, 2015
Certificates of deposit	$	962	$	10,078
Commercial paper		44,130		23,955
Corporate debt securities		212,279		323,219
Securities of government sponsored entities		26,117		30,232
Total investments	$	283,488	$	387,484

Summary of Investments Classified as Available-For-Sale Securities

The following is a summary of investments classified as available-for-sale securities (in thousands):

	Contractual Maturity (in years)		Amortized Cost		Gross Unrealized Gains(1)		Gross Unrealized Losses(1)			Aggregate Estimated Fair Value
September 30, 2016:
Classified as current assets:
Certificates of deposit		Less than 1	$	720	$	1	$	—		$	721
Commercial paper		Less than 1		44,192		—		(62	)		44,130
Corporate debt securities		Less than 1		194,877		12		(88	)		194,801
Securities of government-sponsored entities		Less than 1		13,630		—		(1	)		13,629
Total short-term available-for-sale securities			$	253,419	$	13	$	(151	)	$	253,281
Classified as non-current assets:
Certificates of deposit		1 to 2	$	240	$	1	$	—		$	241
Corporate debt securities		1 to 2		17,506		8		(36	)		17,478
Securities of government-sponsored entities		1 to 2		12,510		—		(22	)		12,488
Total long-term available-for-sale securities			$	30,256	$	9	$	(58	)	$	30,207
December 31, 2015:
Classified as current assets:
Certificates of deposit		Less than 1	$	9,120	$	1	$	(1	)	$	9,120
Commercial paper		Less than 1		23,965		1		(11	)		23,955
Corporate debt securities		Less than 1		254,592		1		(414	)		254,179
Securities of government-sponsored entities		Less than 1		17,762		1		(21	)		17,742
Total short-term available-for-sale securities			$	305,439	$	4	$	(447	)	$	304,996
Classified as non-current assets:
Certificates of deposit		1 to 2	$	960	$	—	$	(2	)	$	958
Corporate debt securities		1 to 2		69,528		—		(488	)		69,040
Securities of government-sponsored entities		1 to 2		12,534		—		(44	)		12,490
Total long-term available-for-sale securities			$	83,022	$	—	$	(534	)	$	82,488

(1) Unrealized gains and losses are included in other comprehensive loss.

Gross Unrealized Losses and Fair Value Available-For-Sale Investments in Unrealized Loss Position

The following table presents gross unrealized losses and fair value for those available-for-sale investments that were in an unrealized loss position as of September 30, 2016 and December 31, 2015, aggregated by investment category and length of time that individual securities have been in a continuous loss position (in thousands):

	Less Than 12 Months					12 Months or Greater					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
September 30, 2016:
Commercial paper	$	44,130	$	(62	)	$	—	$	—		$	44,130	$	(62	)
Corporate debt securities		138,534		(100	)		30,826		(24	)		169,360		(124	)
Securities of government-sponsored entities		22,817		(23	)		—		—			22,817		(23	)
Total	$	205,481	$	(185	)	$	30,826	$	(24	)	$	236,307	$	(209	)
December 31, 2015:
Certificates of deposit	$	5,517	$	(3	)	$	—	$	—		$	5,517	$	(3	)
Commercial paper		16,959		(11	)		—		—			16,959		(11	)
Corporate debt securities		310,160		(880	)		5,521		(22	)		315,681		(902	)
Securities of government-sponsored entities		25,913		(65	)		—		—			25,913		(65	)
Total	$	358,549	$	(959	)	$	5,521	$	(22	)	$	364,070	$	(981	)