INVESTMENTS (Tables)

12 Months Ended

Dec. 31, 2016

Investments Schedule [Abstract]

Amortized Cost, Gross Unrealized Holding Gain or Loss, and Fair Value of Available For Sale Security by Major Security type

The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s available-for-sale securities by major security type at December 31, 2016 and 2015 are summarized in the tables below:

	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Aggregate Fair Value at December 31, 2016
Certificates of deposit	$	2,800	$	—	$	—		$	2,800
Corporate debt securities		633,072		329		(2,277	)		631,124
Commercial paper		16,075		—		—			16,075
U.S. government agency securities		304,635		37		(747	)		303,925
Greek government-issued bonds		48		86		—			134
Total	$	956,630	$	452	$	(3,024	)	$	954,058

	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Aggregate Fair Value at December 31, 2015
Certificates of deposit	$	63,919	$	1	$	—		$	63,920
Corporate debt securities		358,625		20		(732	)		357,913
Commercial paper		12,733		—		—			12,733
U.S. government agency securities		186,882		—		(344	)		186,538
Greek government-issued bonds		48		79		—			127
Total	$	622,207	$	100	$	(1,076	)	$	621,231

Fair Values of Available-For-Sale Securities by Contractual Maturity

The fair values of available-for-sale securities by contractual maturity were as follows:

	December 31,
	2016		2015
Maturing in one year or less	$	381,347	$	195,579
Maturing after one year through five years		572,711		425,652
Total	$	954,058	$	621,231