Segment Reporting - Reconciliation of Segment Earnings to Earnings Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings	$ 8,148	$ 3,851
General and administrative	(4,018)	(3,376)
Interest and other income	24	134
Interest expense	(114)	(220)
Earnings before income taxes	8,058	3,765
Operating segments
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings	12,166	7,227
General and administrative
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings	0	0
General and administrative	(4,018)	(3,376)
Segment reconciling items
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Interest and other income	24	134
Interest expense	$ (114)	$ (220)