Note 2 - Comprehensive Income - Accumulated OCI, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Unrealized holding loss on available-for-sale securities	$ 378,866	$ 380,146
Unrealized holding loss on available-for-sale securities	4,843	(1,192)
Unrealized holding loss on available-for-sale securities	382,840	377,123
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
Unrealized holding loss on available-for-sale securities	(50,842)
Unrealized holding loss on available-for-sale securities	4,761
Unrealized holding loss on available-for-sale securities	(46,081)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Unrealized holding loss on available-for-sale securities	(6,334)
Unrealized holding loss on available-for-sale securities	82
Unrealized holding loss on available-for-sale securities	(6,252)
AOCI Attributable to Parent [Member]
Unrealized holding loss on available-for-sale securities	(57,176)	(57,728)
Unrealized holding loss on available-for-sale securities	4,843	(1,192)
Unrealized holding loss on available-for-sale securities	$ (52,333)	$ (58,920)

Amount after tax and reclassification adjustments of other comprehensive income (loss).

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+ Details

- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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