Note 3 - Fair Value Measurement - Fair Value of Assets Measured on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents, Fair Value	$ 12,872	$ 21,407
Cash and Cash Equivalents, Fair Value	(12,872)	(21,407)
Money Market Funds [Member]
Cash and Cash Equivalents, Fair Value	12,917,000	20,662,000
Cash and Cash Equivalents, Fair Value	(12,917,000)	(20,662,000)
Demand Deposits [Member]
Cash and Cash Equivalents, Fair Value	45,000	745,000
Cash and Cash Equivalents, Fair Value	(45,000)	(745,000)
Fair Value, Inputs, Level 1 [Member]
Cash and Cash Equivalents, Fair Value	12,917	20,662
Cash and Cash Equivalents, Fair Value	(12,917)	(20,662)
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Cash and Cash Equivalents, Fair Value	12,917,000	20,662,000
Cash and Cash Equivalents, Fair Value	(12,917,000)	(20,662,000)
Fair Value, Inputs, Level 1 [Member] | Demand Deposits [Member]
Cash and Cash Equivalents, Fair Value	0	0
Cash and Cash Equivalents, Fair Value	0	0
Fair Value, Inputs, Level 2 [Member]
Cash and Cash Equivalents, Fair Value	0	0
Cash and Cash Equivalents, Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Cash and Cash Equivalents, Fair Value	0	0
Cash and Cash Equivalents, Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] | Demand Deposits [Member]
Cash and Cash Equivalents, Fair Value	0	0
Cash and Cash Equivalents, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member]
Cash and Cash Equivalents, Fair Value	0	0
Cash and Cash Equivalents, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Cash and Cash Equivalents, Fair Value	0	0
Cash and Cash Equivalents, Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Demand Deposits [Member]
Cash and Cash Equivalents, Fair Value	0	(0)
Cash and Cash Equivalents, Fair Value	$ 0	$ 0