DEBT SECURITIES (Tables)

3 Months Ended

Mar. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Schedule of marketable securities

Debt securities consisted of the following (in thousands):

	March 31, 2021		December 31, 2020
Commercial paper	$	158,429	$	135,145
Corporate debt securities	182,388		98,646
Securities of government sponsored entities	31,822		43,026
Total debt securities	$	372,639	$	276,817

Debt securities available for sale

The following is a summary of short-term debt securities classified as available-for-sale as of March 31, 2021 (in thousands):

	Remaining Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses		Aggregate Estimated Fair Value
Commercial paper	Less than 1	$	158,443	$	2	$	(16)	$	158,429
Corporate debt securities	Less than 1	92,166		389		(29)		92,526
Securities of government-sponsored entities	Less than 1	31,821		1		—		31,822
Total maturity less than 1 year		282,430		392		(45)		282,777
Corporate debt securities	1 to 2	89,966		—		(104)		89,862
Total available-for-sale securities		$	372,396	$	392	$	(149)	$	372,639

The following is a summary of short-term debt securities classified as available-for-sale as of December 31, 2020 (in thousands):

	Remaining Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses		Aggregate Estimated Fair Value
Commercial paper	Less than 1	$	135,161	$	1	$	(17)	$	135,145
Corporate debt securities	Less than 1	92,906		723		—		93,629
Securities of government-sponsored entities	Less than 1	43,031		—		(5)		43,026
Total maturity less than 1 year		271,098		724		(22)		271,800
Corporate debt securities	1 to 2	5,013		4		—		5,017
Total available-for-sale securities		$	276,111	$	728	$	(22)	$	276,817

Schedule of securities in an unrealized loss position

The following is a summary of available-for-sale debt securities in an unrealized loss position with no credit losses reported as of March 31, 2021 (in thousands):

	Less Than 12 Months				12 Months or Greater				Total
Description of Securities	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Commercial paper	$	96,435	$	16	$	—	$	—	$	96,435	$	16
Corporate debt securities	117,836		133		—		—		117,836		133
Securities of government-sponsored entities	5,075		—		—		—		5,075		—
Total	$	219,346	$	149	$	—	$	—	$	219,346	$	149

The following is a summary of available-for-sale debt securities in an unrealized loss position with no credit losses reported as of December 31, 2020 (in thousands):

	Less Than 12 Months				12 Months or Greater				Total
Description of Securities	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Commercial paper	$	112,148	$	17	$	—	$	—	$	112,148	$	17
Corporate debt securities	—		—		—		—		—		—
Securities of government-sponsored entities	43,026		5		—		—		43,026		5
Total	$	155,174	$	22	$	—	$	—	$	155,174	$	22