FINANCIAL INSTRUMENTS

6 Months Ended

Jun. 30, 2019

Investments, Debt and Equity Securities [Abstract]

All marketable securities were classified as available-for-sale at June 30, 2019 and December 31, 2018.

The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category as of June 30, 2019 and December 31, 2018, respectively:



	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	$	226,959	$	—	$	—		$	226,959	$	226,959	$	—	$	—

Level 2:
Money market instruments	68,648		—		—			68,648		68,648		—		—
Corporate debt securities	564,624		3,270		(216		)	567,678		—		279,033		288,645
Commercial paper	16,972		—		—			16,972		8,981		7,991		—
U.S. government agency securities	224,071		1,185		(141		)	225,115		2,989		136,502		85,624
Foreign and other	550		147		(1		)	696		—		—		696
Subtotal	874,865		4,602		(358		)	879,109		80,618		423,526		374,965
Total	$	1,101,824	$	4,602	$	(358	)	$	1,106,068	$	307,577	$	423,526	$	374,965



	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.

As of June 30, 2019, the Company’s investments in an unrealized loss position were not significant, and since the Company has the ability and intent to hold all investments that have been in a continuous loss position until maturity or recovery, no other-than-temporary impairment was deemed to have occurred.