Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2020

Marketable Securities

Schedule of marketable securities

Marketable securities consist of the following:

	June 30, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
	Cost		Gain		Loss		Fair Value
(in thousands)
Agency bonds (government sponsored enterprises)	$	24,366	$	83	$	—	$	24,449
Corporate bonds		251,022		1,858		(6)		252,874
Commercial paper		6,962		—		—		6,962
Total	$	282,350	$	1,941	$	(6)	$	284,285

	December 31, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
(in thousands)	Cost		Gain		Loss		Fair Value
Short-term marketable securities:
U.S. treasury securities	$	4,991	$	—	$	—	$	4,991
Agency bonds (government sponsored enterprises)		24,437		15		(1)		24,451
Corporate bonds		271,124		103		(155)		271,072
Total	$	300,552	$	118	$	(156)	$	300,514