Available-for-sale Securities

12 Months Ended

Dec. 31, 2020

Investments Debt And Equity Securities [Abstract]

Available-for-sale securities

4. Available-for-sale securities

The following tables summarize the estimated value of the Company’s available-for-sale marketable securities and cash equivalents and the gross unrealized gains and losses:

	December 31, 2020
			Gross		Gross
	Amortized		unrealized		unrealized			Estimated
	cost		gain		loss			fair value
	(in thousands)
Marketable securities:
Commercial paper	$	69,871	$	—	$	(5	)	$	69,866
U.S. government and agency securities		266,481		131		(5	)		266,607
Total marketable securities		336,352		131		(10	)		336,473
Cash equivalents:
Money market funds		16,696		—		—			16,696
Commercial paper		81,800		—		(3	)		81,797
U.S. government and agency securities		3,913		—		—			3,913
Corporate bonds		3,202		—		(2	)		3,200
Total cash equivalents		105,611		—		(5	)		105,606
Total available-for-sale investments	$	441,963	$	131	$	(15	)	$	442,079

	December 31, 2019
			Gross		Gross
	Amortized		unrealized		unrealized			Estimated
	cost		gain		loss			fair value
	(in thousands)
Marketable securities:
Commercial paper	$	24,446	$	3	$	(1	)	$	24,448
U.S. government and agency securities		42,777		39		(2	)		42,814
Corporate bonds		38,802		37		(2	)		38,837
Total marketable securities		106,025		79		(5	)		106,099
Cash equivalents:
Money market funds		9,369		—		—			9,369
Commercial paper		8,149		—		—			8,149
Total cash equivalents		17,518		—		—			17,518
Total available-for-sale investments	$	123,543	$	79	$	(5	)	$	123,617

The amortized cost and estimated fair value of the Company’s available-for-sale marketable securities and cash equivalents by contractual maturity are summarized below as of December 31, 2020:

	December 31, 2020
			Gross		Gross
	Amortized		unrealized		unrealized			Estimated
	cost		gain		loss			fair value
	(in thousands)
Mature in one year or less	$	409,968	$	127	$	(15	)	$	410,080
Mature after one year through two years		31,995		4		—			31,999
Total marketable securities	$	441,963	$	131	$	(15	)	$	442,079