Fair Value Measurements - Schedule of Amortized Cost (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	$ 186,637,000		$ 186,637,000		$ 199,464,000
Gross Unrealized Gains	2,000		2,000		22,000
Gross Unrealized Losses	(4,323,000)		(4,323,000)		(923,000)
Fair Value	182,316,000		182,316,000		198,563,000
Accrued interest receivable	700,000		700,000		600,000
Realized gains (losses) on marketable securities	0	$ 0	0	$ 0
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	51,074,000		51,074,000		52,791,000
Gross Unrealized Gains	2,000		2,000		11,000
Gross Unrealized Losses	(772,000)		(772,000)		(138,000)
Fair Value	50,304,000		50,304,000		52,664,000
Yankee bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	8,761,000		8,761,000		6,175,000
Gross Unrealized Gains	0		0		1,000
Gross Unrealized Losses	(117,000)		(117,000)		(16,000)
Fair Value	8,644,000		8,644,000		6,160,000
Agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	12,377,000		12,377,000		17,546,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	(101,000)		(101,000)		(16,000)
Fair Value	12,276,000		12,276,000		17,530,000
Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	12,914,000		12,914,000		12,440,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	(867,000)		(867,000)		(211,000)
Fair Value	12,047,000		12,047,000		12,229,000
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	8,453,000		8,453,000		17,694,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	(41,000)		(41,000)		(4,000)
Fair Value	8,412,000		8,412,000		17,690,000
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	30,463,000		30,463,000		27,620,000
Gross Unrealized Gains	0		0		1,000
Gross Unrealized Losses	(479,000)		(479,000)		(86,000)
Fair Value	29,984,000		29,984,000		27,535,000
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	62,595,000		62,595,000		65,198,000
Gross Unrealized Gains	0		0		9,000
Gross Unrealized Losses	(1,946,000)		(1,946,000)		(452,000)
Fair Value	$ 60,649,000		$ 60,649,000		$ 64,755,000