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Note 6 - Fair Value (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) $ / shares	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) $ / shares	Jun. 30, 2023 USD ($)	Jun. 30, 2022
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	$ 0	$ (111)	$ 0	$ (111)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		100		100
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0
Unrealized Gain (Loss) on Investments	$ (24,511)	608	(28,471)	(6,929)
Equity Securities [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net		(111)		(111)
Warrant [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net		$ 0		0
Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member]
Unrealized Gain (Loss) on Investments			(19,700)	(13,100)
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Unrealized Gain (Loss) on Investments			(4,400)	(1,300)
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Unrealized Gain (Loss) on Investments			$ (2,000)	$ (1,900)
The 2026 Notes [Member]
Debt Instrument, Share Price (in dollars per share) | $ / shares	$ 23.88		$ 23.88
The 2026 Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Instrument, Fair Value Disclosure	$ 54,900		$ 54,900
The 2027 Notes [Member]
Debt Instrument, Share Price (in dollars per share) | $ / shares	$ 23.72		$ 23.72
The 2027 Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Debt Instrument, Fair Value Disclosure	$ 54,600		$ 54,600
Asset-backed Notes 2022 [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Instrument, Fair Value Disclosure	$ 100,000		$ 100,000
Measurement Input, Hypothetical Market Yields [Member]
Debt Instrument, Measurement Input					0.25

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