Investments (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Marketable Securities [Line Items]
Amortized Cost	$ 68,304,000		$ 60,909,000
Gains	0		0
Losses	(613,000)		(154,000)
Credit Losses	0		0
Estimated Fair Value	$ 67,691,000		$ 60,755,000
Remaining contractual maturity period	3 years		3 years
Impairments of assets	$ 0	$ 0
Short-term investments
Marketable Securities [Line Items]
Estimated Fair Value	44,888,000		$ 35,068,000
Long-term investments
Marketable Securities [Line Items]
Estimated Fair Value	22,803,000		25,687,000
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	15,241,000		10,243,000
Gains	0		0
Losses	(38,000)		(12,000)
Credit Losses	0		0
Estimated Fair Value	15,203,000		10,231,000
Corporate notes
Marketable Securities [Line Items]
Amortized Cost	53,063,000		50,666,000
Gains	0		0
Losses	(575,000)		(142,000)
Credit Losses	0		0
Estimated Fair Value	$ 52,488,000		$ 50,524,000