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Statements of Cash Flows (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021
Interest		$ 14,240	$ 14,547
Federal income tax		40,200	66,000
Operating cash flows from operating leases		4,086	4,348
Operating cash flows from financing leases		20	4
Financing cash flows from finance leases		1,202	229
Assets acquired under finance lease arrangements		41	183
Assets acquired under operating lease arrangements		5,781	16
Non-cash purchase of property and equipment		17	35
Available-for-sale Securities
Corporate actions related to securities	[1]	17,287	45,392
Equity Securities [Member]
Corporate actions related to securities	[1]	0	$ 527
Conversion of AFS fixed income securities to equity securities		$ 1,463
[1] Examples of corporate actions include like-kind exchanges, non-cash acquisitions, and stock splits.

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