Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Customer Relationships [Member]
Finite-Lived Intangible Assets, Net	$ 7,166,000	$ 11,698,000
Finite-Lived Intangible Assets, Accumulated Amortization	14,938,000	10,406,000
Developed Technology Rights [Member]
Finite-Lived Intangible Assets, Net	787,000	1,292,000
Finite-Lived Intangible Assets, Accumulated Amortization	1,738,000	$ 1,233,000
Prepaid Expenses and Other Current Assets [Member] | New Dawn [Member]
Deferred Set-up Costs, Current	$ 350,000
Minimum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life	5 years
Minimum [Member] | Furniture, Office Equipment, and Software [Member]
Property, Plant and Equipment, Useful Life	3 years
Minimum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment, Useful Life	3 years
Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life	39 years
Maximum [Member] | Furniture, Office Equipment, and Software [Member]
Property, Plant and Equipment, Useful Life	5 years
Maximum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment, Useful Life	10 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	39 years
Product Concentration Risk [Member] | Sales Revenue, Net [Member]
Concentration Risk, Percentage	56.00%	57.00%	53.00%
Daily Journal Non-Consolidated [Member]
Management Incentive Plan Total Percentage of Pre Tax Earnings	4.49%	4.13%	3.85%
Management Incentive Plan Total Amount Paid	$ 271,350	$ 198,915	$ 265,490
Journal Technologies [Member]
Management Incentive Plan Total Percentage of Pre Tax Earnings	8.30%	7.07%
Management Incentive Plan Total Amount Paid	$ 0	$ 10,600
Daily Journal Consolidated [Member]
Management Incentive Plan Total Percentage of Pre Tax Earnings	8.20%	8.20%	8.20%
Management Incentive Plan Total Amount Paid	$ 0	$ 0	$ 0
Management Incentive Plan, Future Commitment [Member]
Other Accrued Liabilities	62,000	47,000
Increase (Decrease) in Other Accrued Liabilities	$ 15,000	$ (733,000)
Other Accrued Liabilities Impact on Earnings Per Share	$ 0.01	$ 0.53
Finite-Lived Intangible Assets, Amortization Expense, Year Three	$ 0
Weighted Average Number of Shares Outstanding, Basic and Diluted	1,380,746	1,380,746	1,380,746
Available-for-sale Securities	$ 166,634,000	$ 166,041,000
Available-for-sale Securities, Gross Unrealized Gain (Loss)	108,256,000	111,498,000
Deferred Tax Liabilities, Investments	42,250,000	43,278,000	$ 48,896,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities		376,000
Other Than Temporary Impairment Losses Investments, Portion Recognized in Earnings, Net of Taxes, Available-for-sale Securities		230,000
Unrealized Loss on Securities			0
Finite-Lived Intangible Assets, Net	7,953,000	12,990,000
Finite-Lived Intangible Assets, Accumulated Amortization	$ 16,676,000	11,639,000
Finite-Lived Intangible Asset, Useful Life	5 years
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 4,895,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	3,058,000
Amortization of Intangible Assets	5,037,000	4,907,000	4,866,000
Goodwill	13,400,000	13,400,000
Depreciation	$ 672,000	624,000	650,000
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Fair Value Inputs, Discount Rate	6.00%
Liability for Uncertainty in Income Taxes, Noncurrent	$ 2,723,000	$ 2,991,000	$ 3,244,000