Note 10 - Fair Value Measurements - Summary of Fair Value Measurements by Level (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Restricted cash and cash equivalents	$ 29,391		$ 24,413
Available-for-sale securities (USD)	119,795	$ 127,727
Total financial assets	440,283
Corporate Debt Securities [Member]
Available-for-sale securities (USD)	488	2,441
Fair Value, Inputs, Level 1 [Member]
Total financial assets	403,751
Fair Value, Inputs, Level 2 [Member]
Total financial assets	36,054
Fair Value, Inputs, Level 3 [Member]
Total financial assets	478
Fair Value, Recurring [Member]
Cash and cash equivalents	136,214	107,076
Restricted cash and cash equivalents	29,391	18,892
Total financial assets		391,591
Fair Value, Recurring [Member] \| Equity Securities [Member]
Marketable equity securities	154,883	137,896
Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities (USD)	56,024	60,171
Fair Value, Recurring [Member] \| Asset-Backed Securities [Member]
Available-for-sale securities (USD)	16,924	17,659
Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Available-for-sale securities (USD)	43,094	45,850
Fair Value, Recurring [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities (USD)	3,753	4,047
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	136,214	107,076
Restricted cash and cash equivalents	29,391	18,892
Total financial assets		352,574
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Equity Securities [Member]
Marketable equity securities	154,883	137,896
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities (USD)	40,169	42,860
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Asset-Backed Securities [Member]
Available-for-sale securities (USD)	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Available-for-sale securities (USD)	43,094	45,850
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities (USD)	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Total financial assets		38,568
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Equity Securities [Member]
Marketable equity securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities (USD)	15,855	17,311
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Asset-Backed Securities [Member]
Available-for-sale securities (USD)	16,446	17,210
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Available-for-sale securities (USD)	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities (USD)	3,753	4,047
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0	0
Restricted cash and cash equivalents	0	0
Total financial assets		0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Equity Securities [Member]
Marketable equity securities	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member]
Available-for-sale securities (USD)	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Asset-Backed Securities [Member]
Available-for-sale securities (USD)	478	449
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| US Treasury Securities [Member]
Available-for-sale securities (USD)	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities (USD)	$ 0	$ 0

Fair value portion of asset recognized for present right to economic benefit.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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