Segment Reporting - Reconciliation of Segment Earnings to Earnings Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings (losses)	$ 2,301	$ 6,056	$ 12,487	$ (10,949)
General and administrative	(3,502)	(1,405)	(9,839)	(7,030)
Interest and other income	37	105	233	614
Interest expense	(178)	(70)	(602)	(288)
Earnings (Losses) before income taxes	2,160	6,091	12,118	(10,623)
Operating segments
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings (losses)	5,803	7,461	22,326	(3,919)
General and administrative
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Operating earnings (losses)	0	0	0	0
General and administrative	(3,502)	(1,405)	(9,839)	(7,030)
Segment reconciling items
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Interest and other income	37	105	233	614
Interest expense	$ (178)	$ (70)	$ (602)	$ (288)