Note 3 - Income Taxes (Details Textual) - USD ($)	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Income Tax Expense (Benefit), Total	$ (8,317,000)	$ 1,717,000	$ 1,620,000	$ (1,280,000)	$ (16,850,000)	$ (100,000)	$ (710,000)	$ (1,880,000)	$ (6,260,000)		$ (19,540,000)		$ (7,150,000)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total									$ 31,476,000		$ 11,339,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent									21.00%	21.00%	24.28%	35.00%	34.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability											$ (16,000,000)
Income Tax Expense (Benefit), Continuing Operations, Revaluation Differences in Deferred Taxes											$ (20,000,000)
Effective Income Tax Rate Reconciliation, Percent, Total									19.90%		172.30%		88.70%
Domestic Tax Authority [Member]
Open Tax Year									2015 2016 2017 2018
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, Total	20,900,000								$ 20,900,000
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member]
Operating Loss Carryforwards, Total	7,700,000								7,700,000
State and Local Jurisdiction [Member] | Other State [Member]
Operating Loss Carryforwards, Total	$ 3,800,000								$ 3,800,000