Note 4 - Related Party Transactions - Significant Activities Between Partnerships (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Net Profits Interests Payments Receivableor Accrued [Member]
Net profits interest receivable	$ 6,822	$ 1,914
Net Profits Interests Revenue [Member]
Net profits interests revenue	17,596	8,714
General and Administrative Amounts (Receivable) Payable[Member]
General and administrative amounts payable	85	486
Total General and Administrative Expenses [Member]
Total general and administrative expenses	$ 571	$ 2,905