Investments in Securities and Derivative Instruments - Textual (Details) - USD ($)	2 Months Ended	3 Months Ended						9 Months Ended
	Feb. 24, 2022	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2022	Jan. 07, 2022	Aug. 31, 2021
Derivatives, Fair Value
Long-term debt, gross		$ 142,796,000						$ 142,796,000		$ 136,932,000
Derivative loss	$ 100,000
Unrealized gain (loss) on interest rate swaps, net of tax		(61,000)	$ 957,000	$ 475,000	$ (20,000)	$ 46,000	$ 11,000	1,371,000	$ 37,000
Gross loss from derivative instrument		100,000						100,000	0
Gross gain from derivative instrument		0			0			46,000.0
Gain from equity investments		300,000			1,700,000			300,000	2,500,000
Loss from equity investments		500,000			1,900,000			800,000	2,100,000
Unsecured Debt | Contrail Aviation Inc.
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)											4.68%
Long-term debt, gross		68,187,000						68,187,000		57,459,000	$ 43,600,000
Unsecured Debt | Parent Company
Derivatives, Fair Value
Long-term debt, gross		47,879,000						47,879,000		51,813,000
Interest Rate Swap
Derivatives, Fair Value
Unrealized gain (loss) on interest rate swaps, net of tax		(100,000)			$ (20,000.0)			1,400,000	$ 37,000.0
Interest Rate Swap | Level 2
Derivatives, Fair Value
Derivative asset		$ 2,900,000						$ 2,900,000		900,000
Term Note A - MBT | Unsecured Debt | Parent Company
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)		3.42%						3.42%				3.42%
Long-term debt, gross		$ 7,961,000						$ 7,961,000		8,542,000
Term Note A - MBT | Interest Rate Swap | Unsecured Debt
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)		4.56%						4.56%
Term Note D - MBT | Unsecured Debt | Parent Company
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)		5.09%						5.09%
Long-term debt, gross		$ 1,355,000						$ 1,355,000		$ 1,405,000