Note 6 - Fair Value Measurements - Fair Value Assets by Investment Category (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Member]
Assets, fair value	$ 71,320	$ 89,371
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	10,995	31,188
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	1,094	639
Other Current Assets [Member]
Assets, fair value	2,584	3,293
Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	179	303
Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	2,405	2,990
Cash [Member] | Cash and Cash Equivalents [Member]
Assets, fair value	59,231	57,544
Cash [Member] | Other Current Assets [Member]
Assets, fair value	0	0
Money Market Funds [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	10,995	31,188
Money Market Funds [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	0	0
Money Market Funds, Rabbi Trust [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	0	0
Money Market Funds, Rabbi Trust [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	179	303
Certificates of Deposit [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	1,094	639
Certificates of Deposit [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	2,405	2,990
Reported Value Measurement [Member]
Assets, fair value	73,904	92,664
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	11,174	31,491
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	3,499	3,629
Reported Value Measurement [Member] | Cash [Member]
Assets, fair value	59,231	57,544
Reported Value Measurement [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	10,995	31,188
Reported Value Measurement [Member] | Money Market Funds, Rabbi Trust [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	179	303
Reported Value Measurement [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	3,499	3,629
Estimate of Fair Value Measurement [Member]
Assets, fair value	74,186	92,961
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	11,174	31,491
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	3,781	3,926
Estimate of Fair Value Measurement [Member] | Cash [Member]
Assets, fair value	59,231	57,544
Estimate of Fair Value Measurement [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	10,995	31,188
Estimate of Fair Value Measurement [Member] | Money Market Funds, Rabbi Trust [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	179	303
Estimate of Fair Value Measurement [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	$ 3,781	$ 3,926