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Note 5 - Derivatives (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Unrealized Gain (Loss) on Derivatives			$ (5,893,000)	$ (5,288,000)
Asset Pledged as Collateral [Member] | Interest Rate Swap Agreements [Member]
Securities Received as Collateral	$ 660,000,000,000		660,000,000,000
Designated as Hedging Instrument [Member]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	157,000,000,000		157,000,000,000
Investment Owned, Cost	183,200,000		183,200,000		$ 189,000,000
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	2,100,000		2,100,000		4,300,000
Derivative, Amount of Hedged Item	60,000,000		60,000,000		$ 60,000,000
Not Designated as Hedging Instrument [Member]
Unrealized Gain (Loss) on Derivatives	$ 266,000	$ 149,000	$ 3,000	$ 201,000

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Amount of hedged item in hedging relationship. Excludes hedged asset or liability.

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Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk. Excludes cumulative basis adjustment related to foreign exchange risk.

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The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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Cost of the investment.

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