INVESTMENTS (Tables)

3 Months Ended

Mar. 31, 2022

INVESTMENTS

Summary of investments in available-for-sale

									Continuous		Continuous
			Gross		Gross				Unrealized		Unrealized
			Unrealized		Unrealized				Loss Position		Loss Position
	Amortized		Holding		Holding		Fair		less than 12		greater than 12
March 31, 2022	Cost		Gains		Losses		Value		Months		Months
Available-for-sale
Short-term:
Commercial paper	$	276,413	$	—	$	—	$	276,413	$	—	$	—
Certificates of deposit		37,010		—		—		37,010		—		—
Municipal securities		168,958		2		482		168,478		482
U.S. government agency securities		78,831		—		342		78,489		342		—
U.S. treasuries		1,161,042		—		3,784		1,157,258		3,784		—
Long-term:
U.S. government agency securities		21,455		—		158		21,297		158		—
Municipal securities		5,284				18		5,266		18
U.S. treasuries		39,313		—		224		39,089		224		—
Total	$	1,788,306	$	2	$	5,008	$	1,783,300	$	5,008	$	—

									Continuous		Continuous
			Gross		Gross				Unrealized		Unrealized
			Unrealized		Unrealized				Loss Position		Loss Position
	Amortized		Holding		Holding		Fair		less than 12		greater than 12
December 31, 2021	Cost		Gains		Losses		Value		Months		Months
Available-for-sale
Short-term:
Commercial paper	$	334,077	$	—	$	—	$	334,077	$	—	$	—
Certificates of deposit		44,502		—		—		44,502		—		—
Municipal securities		666		—		—		666		—		—
U.S. government agency securities		62,687		—		26		62,661		26		—
U.S. treasuries		1,308,536		2		717		1,307,821		717		—
Long-term:
U.S. government agency securities		12,500		—		24		12,476		24		—
U.S. treasuries		87,133		—		190		86,943		190		—
Total	$	1,850,101	$	2	$	957	$	1,849,146	$	957	$	—

Summary of the underlying contractual maturities of investments

	March 31, 2022				December 31, 2021
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than 1 year:
Commercial paper	$	276,413	$	276,413	$	334,077	$	334,077
Municipal securities		168,958		168,478		666		666
U.S. government agency securities		78,831		78,489		62,687		62,661
Certificates of deposit		37,010		37,010		44,502		44,502
U.S. treasuries		1,161,042		1,157,258		1,308,536		1,307,821
Due 1 - 10 years:
U.S. treasuries		39,313		39,089		87,133		86,943
Municipal securities		5,284		5,266		—		—
U.S. government agency securities		21,455		21,297		12,500		12,476
Total	$	1,788,306	$	1,783,300	$	1,850,101	$	1,849,146