Fair Value Measurements - Summary of Asset and Liability Fair Values (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets:
Equity securities	$ 5,718	$ 24,946
Key employee life insurance, cash surrender value	4,507	3,963
Total Assets	82,946	178,548
Liabilities:
Deferred executive compensation liability	11,243	9,783
Total Liabilities	11,243	9,783
Money market funds
Assets:
Available-for-sale	66,322	40,560
Government-related debt securities
Assets:
Available-for-sale		92,928
Corporate debt securities
Assets:
Available-for-sale		8,848
Mutual funds
Assets:
Available-for-sale	6,399	5,582
Bank CDs
Assets:
Available-for-sale		1,721
Level 1
Assets:
Equity securities	5,718	24,946
Key employee life insurance, cash surrender value	0	0
Total Assets	78,430	164,007
Liabilities:
Deferred executive compensation liability	0	0
Total Liabilities	0	0
Level 1 | Money market funds
Assets:
Available-for-sale	66,322	40,560
Level 1 | Government-related debt securities
Assets:
Available-for-sale		92,928
Level 1 | Corporate debt securities
Assets:
Available-for-sale		0
Level 1 | Mutual funds
Assets:
Available-for-sale	6,390	5,573
Level 1 | Bank CDs
Assets:
Available-for-sale		0
Level 2
Assets:
Equity securities	0	0
Key employee life insurance, cash surrender value	4,507	3,963
Total Assets	4,516	14,541
Liabilities:
Deferred executive compensation liability	11,243	9,783
Total Liabilities	11,243	9,783
Level 2 | Accounts Payable and Accrued Liabilities
Liabilities:
Deferred executive compensation liability	2,000	1,300
Level 2 | Other long-term liabilities
Liabilities:
Deferred executive compensation liability	9,200	8,500
Level 2 | Money market funds
Assets:
Available-for-sale	0	0
Level 2 | Government-related debt securities
Assets:
Available-for-sale		0
Level 2 | Corporate debt securities
Assets:
Available-for-sale		8,848
Level 2 | Mutual funds
Assets:
Available-for-sale	9	9
Level 2 | Bank CDs
Assets:
Available-for-sale		1,721
Level 3
Assets:
Equity securities	0	0
Key employee life insurance, cash surrender value	0	0
Total Assets	0	0
Liabilities:
Deferred executive compensation liability	0	0
Total Liabilities	0	0
Level 3 | Money market funds
Assets:
Available-for-sale	0	0
Level 3 | Government-related debt securities
Assets:
Available-for-sale		0
Level 3 | Corporate debt securities
Assets:
Available-for-sale		0
Level 3 | Mutual funds
Assets:
Available-for-sale	$ 0	0
Level 3 | Bank CDs
Assets:
Available-for-sale		$ 0