MARKETABLE SECURITITES (Tables)

9 Months Ended

Sep. 30, 2017

Marketable Securities [Abstract]

Available-for-sale Securities

Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at September 30, 2017, were as follows:

	Amortized Cost		Gross Unrealized					Estimated Fair Market Value
(In thousands)			Gains		Losses
Investments due in 3 months or less:
Commercial paper	$	9,475	$	—	$	—		$	9,475
Corporate securities	19,278		1		(2		)	19,277
Total	28,753		1		(2		)	28,752
Investments due in 4-12 months:
Corporate securities	138,803		28		(78		)	138,753
Government securities	9,337		—		(5		)	9,332
Total	148,140		28		(83		)	148,085
Investments due in 12 months or greater:
Corporate securities	36,224		18		(37		)	36,205
Total	36,224		18		(37		)	36,205
Total marketable securities	$	213,117	$	47	$	(122	)	$	213,042

Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2016, were as follows:

	Amortized Cost		Gross Unrealized					Estimated Fair Market Value
(In thousands)			Gains		Losses
Investments due in 3 months or less:
Commercial paper	$	36,996	$	—	$	—		$	36,996
Corporate securities	9,342		2		(2		)	9,342
Total	46,338		2		(2		)	46,338
Investments due in 4-12 months:
Commercial paper	19,186		—		—			19,186
Corporate securities	59,714		15		(76		)	59,653
Total	78,900		15		(76		)	78,839
Investments due in 12 months or greater:
Corporate securities	63,305		21		(180		)	63,146
Total	63,305		21		(180		)	63,146
Total marketable securities	$	188,543	$	38	$	(258	)	$	188,323