FINANCIAL INSTRUMENTS (Tables)

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Schedule of Cash Cash Equivalents and Available-for-Sale Securities by Significant Investment Category

The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category as of December 31, 2019 and 2018, respectively:


	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value		Cash and Cash Equivalents		Short-term Marketable Securities ⁽¹⁾		Long-term Marketable Securities ⁽²⁾
Level 1:
Cash	$	259,347	$	—	$	—	$	259,347	$	259,347	$	—	$	—

Level 2:
Money market instruments	173,100		—		—		173,100		173,100		—		—
Corporate debt securities	518,523		3,575		(12)		522,086		—		233,294		288,792
U.S. government agency securities	209,633		993		(67)		210,559		4,999		83,067		122,493
Foreign and other	549		145		(1)		693		—		—		693
Subtotal	901,805		4,713		(80)		906,438		178,099		316,361		411,978

Total	$	1,161,152	$	4,713	$	(80)	$	1,165,785	$	437,446	$	316,361	$	411,978


	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Aggregate Fair Value		Cash and Cash Equivalents		Short-term Marketable Securities ⁽¹⁾		Long-term Marketable Securities ⁽²⁾
Level 1:
Cash	$	228,809	$	—	$	—	$	228,809	$	228,809	$	—	$	—

Level 2:
Money market instruments	205,736		—		—		205,736		205,736		—		—
Corporate debt securities	564,852		214		(2,288)		562,778		2,000		376,545		184,233
Commercial paper	77,702		—		—		77,702		21,964		55,738		—
U.S. government agency securities	240,436		144		(697)		239,883		31,474		156,967		51,442
Foreign and other	5,126		139		(1)		5,264		3,999		1,076		189
Subtotal	1,093,852		497		(2,986)		1,091,363		265,173		590,326		235,864

Total	$	1,322,661	$	497	$	(2,986)	$	1,320,172	$	493,982	$	590,326	$	235,864

(1)The Company’s short-term marketable securities mature in one year or less.

(2)The Company’s long-term marketable securities mature between one and five years.