Investments in Securities and Derivative Instruments - Narrative (Details) - USD ($)		2 Months Ended	3 Months Ended
	Mar. 30, 2023	Feb. 24, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Jan. 07, 2022	Aug. 31, 2021
Derivatives, Fair Value
Long-term debt, gross			$ 122,021,000		$ 125,914,000
Derivative loss		$ 100,000
Repayments of long-term debt			1,261,000	$ 836,000
Unrealized gain on interest rate swaps, net of tax			24,000	475,000
Unsecured Debt | Contrail Aviation Inc.
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)						4.68%
Long-term debt, gross			43,363,000		50,621,000	$ 43,600,000
Unsecured Debt | Parent Company
Derivatives, Fair Value
Long-term debt, gross			51,690,000		47,963,000
Interest Rate Swap
Derivatives, Fair Value
Unrealized gain on interest rate swaps, net of tax			24,000	$ 500,000
Interest Rate Swap | Level 2
Derivatives, Fair Value
Derivative asset			$ 2,800,000		2,400,000
Term Note A - MBT | Unsecured Debt | Parent Company
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)			3.42%				3.42%
Long-term debt, gross			$ 7,563,000		7,762,000
Term Note A - MBT | Interest Rate Swap | Unsecured Debt
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)			4.56%
Term Note D - MBT | Unsecured Debt | Parent Company
Derivatives, Fair Value
Interest rate stated percentage (as a percentage)			5.09%
Long-term debt, gross			$ 1,321,000		$ 1,338,000
Term Note G | Unsecured Debt | Contrail Aviation Inc.
Derivatives, Fair Value
Repayments of long-term debt	$ 6,700,000