Note 3 - Fair Value Measurement - Fair Value of Assets Measured on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Money market funds	$ 4,305	$ 7,363
Fair Value, Inputs, Level 1 [Member]
Money market funds	20	6,893
Fair Value, Inputs, Level 2 [Member]
Money market funds	0	0
Fair Value, Inputs, Level 3 [Member]
Money market funds	0	0
Money Market Funds [Member]
Money market funds	20	6,893
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Money market funds	20	6,893
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Money market funds	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Money market funds	0	0
Demand Deposits [Member]
Money market funds	399	45
Demand Deposits [Member] | Fair Value, Inputs, Level 1 [Member]
Money market funds	0	0
Demand Deposits [Member] | Fair Value, Inputs, Level 2 [Member]
Money market funds	0	0
Demand Deposits [Member] | Fair Value, Inputs, Level 3 [Member]
Money market funds	0	$ 0
Savings Account [Member]
Money market funds	3,886
Savings Account [Member] | Fair Value, Inputs, Level 1 [Member]
Money market funds	0
Savings Account [Member] | Fair Value, Inputs, Level 2 [Member]
Money market funds	0
Savings Account [Member] | Fair Value, Inputs, Level 3 [Member]
Money market funds	$ 0