Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Loans (Analysis of Loan Portfolio by Major Types of Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator - interest written off on nonaccrual loans [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 11,322,387		$ 10,641,937
Financing Receivable, Allowance for Credit Loss	(149,935)	$ (146,949)	(155,578)	$ (142,988)	$ (148,294)	$ (149,140)
Loans and Leases Receivable, Net Amount	11,172,452		10,486,359
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator - interest written off on nonaccrual loans [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,251,100		4,981,263
Financing Receivable, Allowance for Credit Loss	(57,119)	(57,307)	(61,254)	(53,250)	(57,050)	(68,934)
Commercial Business [Member]
Financing Receivable, Credit Quality Indicator - interest written off on nonaccrual loans [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,646,956		3,423,268
Financing Receivable, Allowance for Credit Loss	(51,985)	(50,474)	(54,712)	(57,554)	(58,405)	(45,250)
Agriculture [Member]
Financing Receivable, Credit Quality Indicator - interest written off on nonaccrual loans [Line Items]
Loans and Leases Receivable, Net of Deferred Income	853,099		795,715
Financing Receivable, Allowance for Credit Loss	(8,895)	(8,010)	(8,148)	(7,920)	(9,487)	(9,052)
Construction [Member]
Financing Receivable, Credit Quality Indicator - interest written off on nonaccrual loans [Line Items]
Loans and Leases Receivable, Net of Deferred Income	482,211		384,755
Financing Receivable, Allowance for Credit Loss	(5,914)	(5,399)	(5,397)	(6,559)	(6,551)	(7,636)
One-to-Four Family Residential [Member]
Financing Receivable, Credit Quality Indicator - interest written off on nonaccrual loans [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,042,190		1,013,908
Financing Receivable, Allowance for Credit Loss	(24,626)	(24,356)	(24,123)	(16,519)	(15,638)	(16,875)
Consumer Loan [Member]
Financing Receivable, Credit Quality Indicator - interest written off on nonaccrual loans [Line Items]
Loans and Leases Receivable, Net of Deferred Income	46,831		43,028
Financing Receivable, Allowance for Credit Loss	$ (1,396)	$ (1,403)	$ (1,944)	$ (1,186)	$ (1,163)	$ (1,393)