CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES

9 Months Ended

12 Months Ended

Sep. 30, 2020

Dec. 31, 2019

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES

CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES

4.    CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES

The amortized cost, gross unrealized gains and losses, and fair value of cash, cash equivalents, and marketable securities as of September 30, 2020 and December 31, 2019, are as follows (in thousands):

	September 30, 2020
	Cost		Unrealized		Unrealized				Cash and Cash		Marketable
	Basis		Gains		Losses		Fair Value		Equivalents		Securities
Cash	$	405,312		—		—	$	405,312	$	405,312		—
Money market funds		13,707		—		—		13,707		13,707		—
Commercial paper		49,189		2		(1)		49,190		48,340		850
Corporate debt securities		40,813		97		(2)		40,908		2,006		38,902
Asset-backed securities		17,954		50		(6)		17,998		—		17,998
U.S. agency securities		16,980		4		—		16,984		—		16,984
U.S. Treasury securities		6,697		—		—		6,697		—		6,697
Non-U.S. securities		700		—		—		700		—		700
Total	$	551,352	$	153	$	(9)	$	551,496	$	469,365	$	82,131

	December 31, 2019
	Cost		Unrealized		Unrealized				Cash and Cash		Marketable
	Basis		Gains		Losses		Fair Value		Equivalents		Securities
Cash	$	366,358	$	—	$	—	$	366,358	$	366,358	$	—
Money market funds		30,935		—		—		30,935		30,935		—
Commercial paper		19,997		1		(4)		19,994		7,038		12,956
Corporate debt securities		16,417		12		(1)		16,428		—		16,428
U.S. agency securities		749		—		—		749		749		—
U.S. Treasury securities		1,000		—		—		1,000		—		1,000
Asset-backed securities		12,482		12		(2)		12,492		—		12,492
Non-U.S. securities		700		—		—		700		—		700
Total	$	448,638	$	25	$	(7)	$	448,656	$	405,080	$	43,576

A summary of debt securities with unrealized losses aggregated by period of continuous unrealized loss is as follows (in thousands):

September 30, 2020	Less than 12 Months				12 Months or Greater				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
Commercial paper	$	14,797	$	(1)	$	—	$	—	$	14,797	$	(1)
Corporate debt securities		8,212		(2)		—		—		8,212		(2)
Asset-backed securities		2,940		(6)		—		—		2,940		(6)
U.S. Treasury securities		1,699		—		—		—		1,699		—
Total	$	27,648	$	(9)	$	—	$	—	$	27,648	$	(9)

December 31, 2019	Less than 12 Months				12 Months or Greater				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
Commercial paper	$	15,059	$	(4)	$	—	$	—	$	15,059	$	(4)
Corporate-debt securities		3,166		(1)		—		—		3,166		(1)
Asset-backed securities		4,258		(2)		—		—		4,258		(2)
Non-U.S. securities		700		—		—		—		700		—
Total	$	23,183	$	(7)	$	—	$	—	$	23,183	$	(7)

The scheduled contractual maturities of debt securities as of September 30, 2020 are as follows (in thousands):

	Fair Value		Within 1 Year
Commercial paper	$	49,190	$	49,190
Corporate-debt securities		40,908		40,908
Asset-backed securities		17,998		17,998
U.S. agency securities		16,984		16,984
U.S. Treasury securities		6,697		6,697
Non-U.S. securities		700		700
Total	$	132,477	$	132,477

4.CASH, CASH EQUIVALENTS, AND MARKETABLE SECURITIES

The amortized cost, gross unrealized gains and losses, and fair value of cash, cash equivalents, and marketable securities as of December 31, 2019 and 2018, are as follows (in thousands):

	December 31, 2019
	Cost		Unrealized		Unrealized				Cash and Cash		Marketable
	Basis		Gains		Losses		Fair Value		Equivalents		Securities
Cash	$	366,358	$	—	$	—	$	366,358	$	366,358	$	—
Money market funds		30,935		—		—		30,935		30,935		—
Commercial paper		19,997		1		(4)		19,994		7,038		12,956
Corporate debt		16,417		12		(1)		16,428		—		16,428
U.S. agency securities		749		—		—		749		749		—
U.S. Treasury		1,000		—		—		1,000		—		1,000
Asset-backed		12,482		12		(2)		12,492		—		12,492
Non-U.S. securities		700		—		—		700		—		700
Total	$	448,638	$	25	$	(7)	$	448,656	$	405,080	$	43,576

	December 31, 2018
	Cost		Unrealized		Unrealized				Cash and Cash		Marketable
	Basis		Gains		Losses		Fair Value		Equivalents		Securities
Cash	$	2,020	$	—	$	—	$	2,020	$	2,020	$	—
Money market funds		253,911		—		—		253,911		253,911		—
Commercial paper		6,635		—		—		6,635		4,192		2,443
Corporate debt		1,403		—		(1)		1,402		250		1,152
U.S. agency securities		5,456		1		—		5,457		1,995		3,462
U.S. Treasury		999		—		—		999		—		999
Asset-backed		950		—		(2)		948		—		948
Total	$	271,374	$	1	$	(3)	$	271,372	$	262,368	$	9,004

A summary of debt securities with unrealized losses aggregated by period of continuous unrealized loss is as follows (in thousands):

	Less than 12 Months				12 Months or Greater				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
December 31, 2019	Value		Losses		Value		Losses		Value		Losses
Commercial paper	$	15,059	$	(4)	$	—	$	—	$	15,059	$	(4)
Corporate debt		3,166		(1)		—		—		3,166		(1)
Asset-backed		4,258		(2)		—		—		4,258		(2)
Non-U.S. securities		700		—		—		—		700		—
Total	$	23,183	$	(7)	$	—	$	—	$	23,183	$	(7)

	Less than 12 Months				12 Months or Greater				Total
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
December 31, 2018	Value		Losses		Value		Losses		Value		Losses
Commercial paper	$	4,591	$	—	$	—	$	—	$	4,591	$	—
Corporate debt		1,402		(1)		—		—		1,402		(1)
U.S. agency		999		—		—		—		999		—
Asset-backed		—		—		948		(2)		948		(2)
Total	$	6,992	$	(1)	$	948	$	(2)	$	7,940	$	(3)

The scheduled contractual maturities of debt securities as of December 31, 2019 are as follows (in thousands):

					After
					1 Year
			Within		through
December 31, 2019	Fair Value		1 Year		5 Years
Commercial paper	$	19,994	$	19,994	$	—
Corporate debt		16,428		16,428		—
U.S. agency securities		749		749		—
U.S. Treasury		1,000		1,000		—
Asset-backed		12,492		—		12,492
Non-U.S. securities		700		700		—
Total	$	51,363	$	38,871	$	12,492