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Investments - Summary of Available for Sale Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Total
Total, amortized cost	$ 11,409	$ 10,806
Total, gross unrealized gains	2,023	2,320
Total, gross unrealized losses	(63)	(63)
Total, estimated fair value	13,369	13,063
Equities
Equity securities
Equity securities, amortized cost		172
Equity securities, gross unrealized gains		628
Equity securities, gross unrealized losses		0
Equity securities, estimated fair value		800
Mutual funds
Equity securities
Equity securities, amortized cost	6,001	5,323
Equity securities, gross unrealized gains	1,649	1,432
Equity securities, gross unrealized losses	0	0
Equity securities, estimated fair value	7,650	6,755
U.S. Government and agency securities
Available-for-sale securities
Available-for-sale securities, amortized cost	2,742	2,317
Available-for-sale securities, gross unrealized gains	0	1
Available-for-sale securities, gross unrealized losses	(4)	(4)
Available-for-sale securities, estimated fair value	2,738	2,314
Corporate bonds
Available-for-sale securities
Available-for-sale securities, amortized cost	2,559	2,879
Available-for-sale securities, gross unrealized gains	374	259
Available-for-sale securities, gross unrealized losses	(7)	(6)
Available-for-sale securities, estimated fair value	2,926	3,132
Asset-backed securities and collateralized mortgage obligations
Available-for-sale securities
Available-for-sale securities, amortized cost	107	115
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	(52)	(53)
Available-for-sale securities, estimated fair value	$ 55	$ 62

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