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Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Interest	$ 26,639	$ 28,930	$ 30,464
Federal income tax	75,000	100,000	47,000
Operating cash flows from operating leases	8,148	7,935	9,498
Operating cash flows from financing leases	46	35	15
Financing cash flows from financing leases	2,438	1,768	550
Assets acquired under finance lease arrangements	707	6,709	324
Assets acquired under operating lease arrangements	16,649	3,272	22,390
Non-cash purchase of property and equipment	70	472	590
Available-for-sale Securities [Member]
Corporate actions related to securities	38,106	56,365	55,446
Held-to-maturity Securities [Member]
Corporate actions related to securities	0	0	2,589
Equity Securities [Member]
Corporate actions related to securities	0	30,666	10,890
Conversion of AFS fixed income securities to equity securities	$ 1,463	$ 15,139	$ 0

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