Note 10 - Fair Value Measurements - Summary of Fair Value Measurements by Level (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Restricted cash and cash equivalents	$ 20,905		$ 30,267
Available-for-sale securities	122,912	$ 119,804
Corporate Debt Securities [Member]
Available-for-sale securities	63,095	57,471
Fair Value, Recurring [Member]
Cash and cash equivalents	130,629	76,121
Restricted cash and cash equivalents	20,905	20,801
Total financial assets	458,682	379,980
Fair Value, Recurring [Member] | Equity Securities [Member]
Marketable equity securities	184,236	163,254
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Available-for-sale securities	63,095	57,471
Fair Value, Recurring [Member] | Asset-Backed Securities [Member]
Available-for-sale securities	12,942	14,410
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Available-for-sale securities	43,771	44,186
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	3,104	3,737
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	130,629	76,121
Restricted cash and cash equivalents	20,905	20,801
Total financial assets	414,819	348,824
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Marketable equity securities	184,236	163,254
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Available-for-sale securities	34,482	43,656
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-Backed Securities [Member]
Available-for-sale securities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Available-for-sale securities	43,771	44,186
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	796	806
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	43,863	31,156
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	28,613	13,815
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-Backed Securities [Member]
Available-for-sale securities	12,942	14,410
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
Available-for-sale securities	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	$ 2,308	$ 2,931