Allowance for Credit Losses - By Loan Class (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	$ 160,443	$ 158,707	$ 159,174	$ 156,537	$ 156,537
Losses charged to allowance	(2,068)	(9,978)	(4,695)	(11,977)
Recoveries credited to allowance	534	1,856	1,406	2,696
Net losses charged to allowance	(1,534)	(8,122)	(3,289)	(9,281)
Provision (credit) charged to operations	11,105	4,398	14,129	7,727
Balance at the end of the period	170,014	154,983	170,014	154,983	159,174
Commercial, financial and agricultural \| Domestic \| Commercial
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	29,491	28,946	27,929	29,853	29,853
Losses charged to allowance	(1,794)	(1,749)	(4,235)	(3,537)	(7,673)
Recoveries credited to allowance	498	1,626	1,219	2,447
Net losses charged to allowance	(1,296)	(123)	(3,016)	(1,090)
Provision (credit) charged to operations	6,816	(409)	10,098	(349)
Balance at the end of the period	35,011	28,414	35,011	28,414	27,929
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	45,852	45,667	46,413	43,990	43,990
Recoveries credited to allowance		106		112
Net losses charged to allowance		106		112
Provision (credit) charged to operations	1,164	887	603	2,558
Balance at the end of the period	47,016	46,660	47,016	46,660	46,413
Commercial, financial and agricultural \| Domestic \| Commercial Real Estate Multifamily Receivable [Member]
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	18,008	4,857	14,713	4,869	4,869
Provision (credit) charged to operations	347	3,143	3,642	3,131
Balance at the end of the period	18,355	8,000	18,355	8,000	14,713
Commercial real estate \| Domestic \| Commercial
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period			48,907	60,639	60,639
Losses charged to allowance				(8,121)
Net losses charged to allowance				(8,121)
Provision (credit) charged to operations			(344)	1,547
Balance at the end of the period	48,563	54,065	48,563	54,065	48,907
Commercial real estate \| Domestic \| Commercial real estate construction development
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	46,061	61,865
Losses charged to allowance		(8,121)			(8,122)
Net losses charged to allowance		(8,121)
Provision (credit) charged to operations	2,502	321
Balance at the end of the period	48,563	54,065	48,563	54,065
Real estate - mortgage \| Domestic \| Residential First Lien
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	6,803	5,669	6,725	5,528	5,528
Losses charged to allowance	(52)	(3)	(204)	(49)	(104)
Recoveries credited to allowance	2	13	142	15
Net losses charged to allowance	(50)	10	(62)	(34)
Provision (credit) charged to operations	281	563	371	748
Balance at the end of the period	7,034	6,242	7,034	6,242	6,725
Real estate - mortgage \| Domestic \| Residential Junior Lien
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	9,163	10,077	9,420	10,031	10,031
Losses charged to allowance	(113)	(82)	(113)	(202)	(260)
Recoveries credited to allowance	33	109	41	116
Net losses charged to allowance	(80)	27	(72)	(86)
Provision (credit) charged to operations	(154)	(106)	(419)	53
Balance at the end of the period	8,929	9,998	8,929	9,998	9,420
Consumer \| Domestic
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	253	262	279	281	281
Losses charged to allowance	(109)	(23)	(143)	(68)	(200)
Recoveries credited to allowance	1	2	4	6
Net losses charged to allowance	(108)	(21)	(139)	(62)
Provision (credit) charged to operations	106	32	111	54
Balance at the end of the period	251	273	251	273	279
Foreign \| Foreign
Rollforward of transactions in the allowance for credit loan losses by loan class
Balance at the beginning of the period	4,812	1,364	4,788	1,346	1,346
Provision (credit) charged to operations	43	(33)	67	(15)
Balance at the end of the period	$ 4,855	$ 1,331	$ 4,855	$ 1,331	$ 4,788

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

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Amount, excluding accrued interest, of decrease (increase) in allowance for credit loss on financing receivable from writeoff (recovery). Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

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