Investments (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2021

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Schedule of held-to-maturity investments

			Fair Value Measurements as of March 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
Held-to-maturity investments
Commercial paper	$	116,658	$	—	$	(24	)	$	116,634
State and municipal bonds		15,805		—		(21	)		15,784
Corporate bonds and notes		164,847		—		(644	)		164,203
Total held-to-maturity investments	$	297,310	$	—	$	(689	)	$	296,621

			Fair Value Measurements as of December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
Held-to-maturity investments
Treasury securities	$	149,996	$	—	$	(1	)	$	149,995
Commercial paper		37,963		—		(15	)		37,948
Corporate bonds and notes		49,892		—		(63	)		49,829
Total held-to-maturity investments	$	237,851	$	—	$	(79	)	$	237,772

			Fair Value Measurements as of December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
Held-to-maturity investments
Treasury securities	$	149,996	$	-	$	(1	)	$	149,995
Commercial paper		37,963		-		(15	)		37,948
Corporate bonds and notes		49,892		-		(63	)		49,829
Total held-to-maturity investments	$	237,851	$	-	$	(79	)	$	237,772

Schedule of investment maturity

	March 31, 2021				December 31, 2020
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(in thousands)				(in thousands)
Due in one year or less	$	144,829	$	144,788	$	201,881	$	201,864
Due after one year through five years		152,481		151,833		35,970		35,908
Total held-to-maturity securities	$	297,310	$	296,621	$	237,851	$	237,772

Schedule of investment maturity

	December 31, 2020
	Amortized Cost		Fair Value
	(in thousands)
Due in one year or less	$	201,881	$	201,864
Due after one year through five years		35,970		35,908
Total held-to-maturity securities	$	237,851	$	237,772