Segment Reporting - Reconciliation of Segment Earnings to Earnings Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings	$ 2,993	$ 2,301	$ 14,101	$ 12,487
General and administrative	(4,630)	(3,502)	(12,860)	(9,839)
Interest and other income	338	37	665	233
Interest expense	(119)	(178)	(369)	(602)
Earnings before income taxes	3,212	2,160	14,397	12,118
Operating segments
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings	7,623	5,803	26,961	22,326
General and administrative
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings	0	0	0	0
General and administrative	(4,630)	(3,502)	(12,860)	(9,839)
Segment reconciling items
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Interest and other income	338	37	665	233
Interest expense	$ (119)	$ (178)	$ (369)	$ (602)