Investments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 99,943,000	$ 53,451,000
Unrealized Gain	0	1,000
Unrealized Loss	(109,000)	(4,000)
Fair Value	99,834,000	53,448,000
Credit losses on available for sale securities recognized	0	0	$ 0
Corporate Debt Securities | Corporate bonds and notes—short-term
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	75,896,000	38,888,000
Unrealized Gain	0	0
Unrealized Loss	(26,000)	(4,000)
Fair Value	75,870,000	38,884,000
Corporate Debt Securities | Corporate bonds and notes—long-term
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	24,047,000	14,563,000
Unrealized Gain	0	1,000
Unrealized Loss	(83,000)	0
Fair Value	$ 23,964,000	$ 14,564,000
Minimum | Corporate bonds and notes—short-term
Debt Securities, Available-for-sale [Line Items]
Weighted average maturity of short-term investments	4 months 24 days	7 months 6 days
Maximum | Corporate bonds and notes—long-term
Debt Securities, Available-for-sale [Line Items]
Weighted average maturity of short-term investments	1 year 2 months 12 days	1 year 6 months