Note 10 - Subsequent Events (Details Textual) - USD ($)		6 Months Ended
	Jul. 02, 2021	Jun. 30, 2021	Jun. 30, 2020	May 31, 2017
Repayments of Long-term Debt, Total		$ 27,000	$ 23,000
Senior Secured Debt [Member]
Debt Instrument, Face Amount				$ 60,000,000
Subsequent Event [Member]
Deposits, Segregated Account, Pre-fund Eight Quarterly Dividend Payments	$ 10,200,000
Subsequent Event [Member] | Warrants Issued to Lenders [Member]
Class of Warrant or Right, Issued During Period (in shares)	2
Subsequent Event [Member] | Warrant A Issued to Lenders [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)	500,000
Subsequent Event [Member] | Warrant B Issued to Lenders [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares)	500,000
Subsequent Event [Member] | A Warrant [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 17.38
Subsequent Event [Member] | B Warrant [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 21.72
Warrants and Rights Outstanding, Term (Day)	180 days
Subsequent Event [Member] | Senior Secured Debt [Member]
Repayments of Long-term Debt, Total	$ 77,500,000
Subsequent Event [Member] | New Loan [Member]
Debt Instrument, Face Amount	$ 50,000,000
Debt Instrument, Interest Rate, Stated Percentage	7.00%
Subsequent Event [Member] | Apollo [Member]
Stock Issued During Period, Shares, New Issues (in shares)	363,566
Subsequent Event [Member] | BRS [Member] | Senior Secured Debt [Member] | Apollo [Member]
Payments for Debt Restructuring Fee	$ 1,925,000
Subsequent Event [Member] | Affiliate of BRS [Member] | Senior Secured Debt Issued By Cadiz [Member]
Payments to Acquire Notes Receivable	$ 77,500,000
Depository Shares [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)	2,000,000
Preferred Stock, Shares Per Depository Share (in dollars per share)	$ 0.001
Preferred Stock, Liquidation Preference Per Share (in dollars per share)	$ 25.00
Depository Shares [Member] | Subsequent Event [Member] | Sale Including Overallotment Option [Member]
Stock Issued During Period, Shares, New Issues (in shares)	2,300,000
Series A Preferred Stock [Member] | Subsequent Event [Member]
Proceeds From Issuance of Preferred Stock, Net of Issuance Costs	$ 54,000,000
Preferred Stock, Dividend Rate, Percentage	8.875%
Preferred Stock, Liquidation Preference Per Share (in dollars per share)	$ 25,000.00