Investments in Securities and Derivative Instruments (Details Textual) - USD ($)	3 Months Ended				6 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Derivatives, Fair Value
Unrealized gain (loss) on interest rate swaps, net of tax	$ 55,000	$ (26,000)	$ (88,000)	$ (176,000)	$ 29,000	$ (264,000)
Margin accounts outstanding	600,000		18,100		600,000	18,100
Cash margin balances related to exchange-traded equity securities	$ 700,000		$ 200,000		$ 700,000	$ 200,000
Interest rate on margin account borrowings (percent)	5.50%				5.50%
Gain from equity investments	$ 100,000				$ 700,000
Loss from equity investments	300,000				700,000
Level 1
Derivatives, Fair Value
Gross gain from derivative instrument	400,000				700,000
Gross loss from derivative instrument	100,000				100,000
Interest Rate Swap
Derivatives, Fair Value
Unrealized gain (loss) on interest rate swaps, net of tax	(55,000.0)				29,000.0
Interest Rate Swap | Level 2 | Other non-current liabilities
Derivatives, Fair Value
Derivative liability	$ 900,000				$ 900,000		$ 900,000
Unsecured Debt | Interest Rate Swap | Term Note A - MB&T
Derivatives, Fair Value
Interest rate	4.56%				4.56%
Unsecured Debt | Interest Rate Swap | Term Note D - MB&T
Derivatives, Fair Value
Interest rate	5.09%				5.09%