Note 3 - Investments - Security Holdings in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 Months, fair value	$ 104,439	$ 354,769
Less than 12 Months, Accumulated Loss	(1,833)	(8,726)
12 Months or Longer, fair value	270,911	309,203
12 Months or Longer, Accumulated Loss	(17,678)	(28,531)
Fair value	375,350	663,972
Accumulated Loss	(19,511)	(37,257)
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 Months, fair value	2,006	16,507
Less than 12 Months, Accumulated Loss	(38)	(65)
12 Months or Longer, fair value	5,704	14,291
12 Months or Longer, Accumulated Loss	(188)	(584)
Fair value	7,710	30,798
Accumulated Loss	(226)	(649)
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 Months, fair value	5,157	2,614
Less than 12 Months, Accumulated Loss	(441)	(419)
12 Months or Longer, fair value	9,509	5,076
12 Months or Longer, Accumulated Loss	(553)	(438)
Fair value	14,666	7,690
Accumulated Loss	(994)	(857)
Special Revenue Excluding Asset Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 Months, fair value	0	2,182
Less than 12 Months, Accumulated Loss	0	(426)
12 Months or Longer, fair value	15,185	21,733
12 Months or Longer, Accumulated Loss	(1,887)	(3,308)
Fair value	15,185	23,915
Accumulated Loss	(1,887)	(3,734)
Corporate Debt Securities and Other Debt Obligations [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 Months, fair value	49,963	181,179
Less than 12 Months, Accumulated Loss	(948)	(4,996)
12 Months or Longer, fair value	160,780	176,531
12 Months or Longer, Accumulated Loss	(7,456)	(13,353)
Fair value	210,743	357,710
Accumulated Loss	(8,404)	(18,349)
Asset-Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Less than 12 Months, fair value	47,313	152,287
Less than 12 Months, Accumulated Loss	(406)	(2,820)
12 Months or Longer, fair value	79,733	91,572
12 Months or Longer, Accumulated Loss	(7,594)	(10,848)
Fair value	127,046	243,859
Accumulated Loss	$ (8,000)	$ (13,668)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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