Federal Income Tax - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Computed expected income tax expense (benefit)	$ (8,339)	$ 2,536	$ 20,337
Tax-exempt municipal bond interest income	(2,763)	(3,115)	(3,412)
Nontaxable dividend income	(269)	(378)	(361)
Compensation	596	582	770
Research & development credit	540	(1,591)	(1,545)
Other, net	215	(988)	460
Total	$ (10,021)	$ (2,954)	$ 16,249

Effective Income Tax Rate Reconciliation, Compensation, Amount

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Income Tax Reconciliation, Tax Exempt Income, Dividend

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Income Tax Reconciliation, Tax Exempt Income, Interest

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority noncontrolling interest income (loss), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, increase (decrease) in enacted tax rate, prior year income taxes, increase (decrease) in deferred tax asset valuation allowance, and other adjustments.

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