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Note 6 - Fair Value (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Jun. 30, 2022
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	$ 0	$ (5,000)	$ 0	$ (5,111)
Unrealized Gain (Loss) on Investments	$ 29,335	(17,518)	864	(24,448)
Equity Securities [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net		0		(111)
Warrant [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net		0		0
Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		$ 5,000		5,000
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				100
Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member]
Unrealized Gain (Loss) on Investments			(6,000)	(33,600)
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Unrealized Gain (Loss) on Investments			(4,500)	(1,600)
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Unrealized Gain (Loss) on Investments			$ (300)	$ (2,100)
The 2026 Notes [Member]
Debt Instrument, Share Price (in dollars per share) | $ / shares	$ 24.3		$ 24.3
The 2026 Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Instrument, Fair Value Disclosure	$ 55,900		$ 55,900
The 2027 Notes [Member]
Debt Instrument, Share Price (in dollars per share) | $ / shares	$ 24.16		$ 24.16
The 2027 Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Instrument, Fair Value Disclosure	$ 55,600		$ 55,600
Asset-backed Notes 2022 [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Instrument, Fair Value Disclosure	$ 91,000		$ 91,000
Measurement Input, Hypothetical Market Yields [Member]
Debt Instrument, Measurement Input					0.25

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