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Allowance for Credit Losses (Impairment By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	$ 3,277	$ 12,675
Loans Individually Evaluated for Impairment, Allowance	481	365
Loans Collectively Evaluated for Impairment, Recorded Investment	7,585,958	6,882,271
Loans Collectively Evaluated for Impairment, Allowance	101,684	59,913
Commercial, financial and agricultural | Domestic | Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,444	1,935
Loans Individually Evaluated for Impairment, Allowance	411	249
Loans Collectively Evaluated for Impairment, Recorded Investment	1,876,535	1,290,725
Loans Collectively Evaluated for Impairment, Allowance	21,733	10,895
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	501	1,208
Loans Collectively Evaluated for Impairment, Recorded Investment	2,110,448	1,895,539
Loans Collectively Evaluated for Impairment, Allowance	23,689	16,533
Commercial, financial and agricultural | Domestic | Commercial Real Estate: multifamily
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	137	165
Loans Collectively Evaluated for Impairment, Recorded Investment	437,801	190,265
Loans Collectively Evaluated for Impairment, Allowance	4,503	1,786
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	911	938
Loans Individually Evaluated for Impairment, Allowance	70	116
Loans Collectively Evaluated for Impairment, Recorded Investment	1,942,519	2,184,945
Loans Collectively Evaluated for Impairment, Allowance	38,013	18,037
Real estate - mortgage | Domestic | Residential First Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	243	6,278
Loans Collectively Evaluated for Impairment, Recorded Investment	409,772	427,623
Loans Collectively Evaluated for Impairment, Allowance	3,529	3,762
Real estate - mortgage | Domestic | Residential Junior Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	38	692
Loans Collectively Evaluated for Impairment, Recorded Investment	623,593	705,784
Loans Collectively Evaluated for Impairment, Allowance	9,305	7,535
Consumer | Domestic
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	3	1,195
Loans Collectively Evaluated for Impairment, Recorded Investment	41,107	46,605
Loans Collectively Evaluated for Impairment, Allowance	274	542
Foreign | Foreign
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment		264
Loans Collectively Evaluated for Impairment, Recorded Investment	144,183	140,785
Loans Collectively Evaluated for Impairment, Allowance	$ 638	$ 823

X

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
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+ References

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-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
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