Note 6 - Fair Value Measurements - Fair Value Assets by Investment Category (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Member]
Assets, fair value	$ 134,266	$ 89,371
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	58,208	31,188
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	1,503	639
Other Current Assets [Member]
Assets, fair value	2,512	3,293
Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	685	303
Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	1,827	2,990
Cash [Member] | Cash and Cash Equivalents [Member]
Assets, fair value	74,555	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	58,208	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	685	303
Certificates of Deposit [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	1,503	639
Certificates of Deposit [Member] | Other Current Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	1,827	2,990
Reported Value Measurement [Member]
Assets, fair value	136,777	92,664
Reported Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	58,893	31,491
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	3,329	3,629
Reported Value Measurement [Member] | Cash [Member]
Assets, fair value	74,555	57,544
Reported Value Measurement [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	58,208	31,188
Reported Value Measurement [Member] | Money Market Funds, Rabbi Trust [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	685	303
Reported Value Measurement [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	3,329	3,629
Estimate of Fair Value Measurement [Member]
Assets, fair value	137,156	92,961
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	58,893	31,491
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	3,708	3,926
Estimate of Fair Value Measurement [Member] | Cash [Member]
Assets, fair value	74,555	57,544
Estimate of Fair Value Measurement [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	58,208	31,188
Estimate of Fair Value Measurement [Member] | Money Market Funds, Rabbi Trust [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value	685	303
Estimate of Fair Value Measurement [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value	$ 3,708	$ 3,926