Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2019

Marketable Securities

Schedule of available-for-sale securities

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

Schedule of available-for-sale maturities

	December 31, 2019
			Fair
(in thousands)	Cost		Value
Maturities:
Within 1 year	$	168,186	$	168,204
From more than 1 to 5 years		132,366		132,310
Total investments available for sale	$	300,552	$	300,514