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Note 6 - Fair Value (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2025 USD ($) $ / shares	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Jun. 30, 2025 USD ($) $ / shares	Jun. 30, 2024 USD ($)	Jun. 30, 2022
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	$ 0	$ 0		$ 0
Unrealized Gain (Loss) on Investments	$ (22,156)	$ (24,511)		(54,313)	$ (28,471)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			$ 0
Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member]
Unrealized Gain (Loss) on Investments				45,500	19,700
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Unrealized Gain (Loss) on Investments				14,700	4,400
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Unrealized Gain (Loss) on Investments				$ 3,900	$ 2,000
The 2026 Notes [Member]
Debt Instrument, Share Price (in dollars per share) | $ / shares	$ 24.75			$ 24.75
The 2026 Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Instrument, Fair Value Disclosure	$ 56,900			$ 56,900
The 2027 Notes [Member]
Debt Instrument, Share Price (in dollars per share) | $ / shares	$ 24.75			$ 24.75
The 2027 Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Instrument, Fair Value Disclosure	$ 56,900			$ 56,900
The 2031 Convertible Notes [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Instrument, Fair Value Disclosure	7,400			7,400
Asset-backed Notes 2022 [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Instrument, Fair Value Disclosure	$ 34,200			$ 34,200
Measurement Input, Hypothetical Market Yields [Member]
Debt Instrument, Measurement Input						0.25

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