Consolidated Balance Sheets (Unaudited) - USD ($)	Mar. 31, 2024	Sep. 30, 2023
Current assets
Cash and cash equivalents	$ 10,557,000	$ 20,844,000
Restricted cash	2,144,000	2,100,000
Non-qualified deferred compensation plan - trust account asset value	522,000	194,000
Marketable securities at fair value -- common stocks	297,003,000	303,128,000
Accounts receivable, less allowance for doubtful accounts of $250,000 at March 31, 2024 and September 30, 2023	15,624,000	18,687,000
Inventories	64,000	72,000
Prepaid expenses and other current assets	514,000	380,000
Total current assets	326,428,000	345,405,000
Property, Plant and Equipment, Net [Abstract]
Land, buildings and improvements	16,418,000	16,400,000
Furniture, office equipment and computer software	1,697,000	1,703,000
Machinery and equipment	1,521,000	1,521,000
Property, Plant and Equipment, Gross	19,636,000	19,624,000
Less accumulated depreciation	(10,386,000)	(10,264,000)
Property, Plant and Equipment, Net	9,250,000	9,360,000
Operating lease right-of-use assets	69,000	95,000
Total assets	335,747,000	354,860,000
Liabilities, Current [Abstract]
Accounts payable	6,070,000	6,643,000
Accrued liabilities	6,054,000	8,789,000
Income tax payable	2,550,000	1,069,000
Note payable collateralized by real estate	161,000	158,000
Total current liabilities	36,397,000	42,198,000
Liabilities, Noncurrent [Abstract]
Investment margin account borrowings	29,421,000	75,000,000
Note payable collateralized by real estate	1,038,000	1,120,000
Deferred maintenance agreements	816,000	1,000,000
Accrued liabilities	3,421,000	4,274,000
Accrued non-qualified deferred compensation	509,000	200,000
Deferred income taxes	35,646,000	30,599,000
Total long-term liabilities	70,851,000	112,193,000
Commitments and Contingencies
Equity, Attributable to Parent [Abstract]
Preferred stock, $.01 par value, 5,000,000 shares authorized and no shares issued	0	0
Common stock, $.01 par value, 5,000,000 shares authorized; 1,805,053 shares issued, including 428,027 treasury shares, at March 31, 2024 and September 30, 2023	14,000	14,000
Additional paid-in capital	1,755,000	1,755,000
Retained earnings	226,730,000	198,700,000
Total shareholders' equity	228,499,000	200,469,000
Liabilities and Equity	335,747,000	354,860,000
Subscription and Circulation [Member]
Liabilities, Current [Abstract]
Deferred subscriptions	2,562,000	2,678,000
Professional Fees [Member]
Liabilities, Current [Abstract]
Deferred subscriptions	4,228,000	5,828,000
License and Maintenance [Member]
Liabilities, Current [Abstract]
Deferred subscriptions	$ 14,772,000	$ 17,033,000