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Statements of Cash Flows (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021
Interest		$ 22,699	$ 23,278
Federal income tax		61,000	93,000
Operating cash flows from operating leases		6,096	6,480
Operating cash flows from financing leases		33	5
Financing cash flows from finance leases		1,819	298
Assets acquired under finance lease arrangements		650	183
Assets acquired under operating lease arrangements		15,514	273
Non-cash purchase of property and equipment		0	0
Available-for-sale Securities
Corporate actions related to securities	[1]	32,546	50,501
Equity Securities [Member]
Corporate actions related to securities	[1]	0	527
Conversion of AFS fixed income securities to equity securities		$ 1,463	$ 0
[1] Examples of corporate actions include like-kind exchanges, non-cash acquisitions, and stock splits.

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