INVESTMENTS (Tables)

3 Months Ended

Mar. 31, 2017

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 March 31, 2017 and December 31, 2016 are summarized in the tables below:

	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Aggregate Fair Value at March 31, 2017
Corporate debt securities	$	603,611	$	395	$	(1,713	)	$	602,293
Commercial paper		4,234		—		—			4,234
U.S. government agency securities		257,525		15		(759	)		256,781
Greek government-issued bonds		48		93		—			141
Total	$	865,418	$	503	$	(2,472	)	$	863,449

	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

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

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

	March 31,		December 31,
	2017		2016
Maturing in one year or less	$	329,821	$	381,347
Maturing after one year through five years		533,628		572,711
Total	$	863,449	$	954,058