Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2020

Marketable Securities

Schedule of marketable securities

			Gross		Gross
	Amortized		Unrealized		Unrealized
March 31, 2020	Cost		Gains		Losses		Fair Value
(in thousands)
Money Market Funds	$	49,800	$	—	$	—	$	49,800
Corporate Securities		333,259		22		(590)		332,691
Government Securities		201,748		1,634		—		203,382
	$	584,807	$	1,656	$	(590)	$	585,873
Reported as
Cash and cash equivalents							$	49,800
Marketable securities								536,073
Total investments							$	585,873
			Gross		Gross
	Amortized		Unrealized		Unrealized
December 31, 2019	Cost		Gains		Losses		Fair Value
(in thousands)
Money Market Funds	$	32,009	$	—	$	—	$	32,009
Corporate Securities		281,586		195		(30)		281,751
Government Securities		268,239		1,006		—		269,245
	$	581,834	$	1,201	$	(30)	$	583,005
Reported as
Cash and cash equivalents							$	32,009
Marketable securities								550,996
Total investments							$	583,005

Schedule of maturities of marketable securities

	Amortized		Estimated
March 31, 2020	Cost		Fair Value
(in thousands)
Mature in one year or less	$	496,586	$	497,841
Mature within two years		38,421		38,232
	$	535,007	$	536,073

Schedule of unrealized losses on available-for-sale investments

The unrealized losses on available-for-sale investments and their related fair values as of March 31, 2020 and December 31, 2019 are as follows:

	Less than 12 months				12 months or greater
			Unrealized				Unrealized
March 31, 2020	Fair value		losses		Fair value		losses
(in thousands)
Corporate Securities	$	141,723	$	(401)	$	38,232	$	(189)
	Less than 12 months				12 months or greater
			Unrealized				Unrealized
December 31, 2019	Fair value		losses		Fair value		losses
(in thousands)
Corporate Securities	$	46,303	$	(24)	$	13,992	$	(6)