Loans - Schedule of composition of loan portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 6,871,122	$ 7,177,785
Financing Receivable, Allowance for Credit Loss	(83,197)	(85,675)	$ (56,679)	$ (51,512)
Net loans	6,787,925	7,092,110
Interest Receivable		20,653
Loans and Leases Receivable, Recorded Investment		7,198,438
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,298,626	1,588,989
Financing Receivable, Allowance for Credit Loss	(14,025)	(25,608)	(20,203)	(16,777)
Interest Receivable		6,528
Loans and Leases Receivable, Recorded Investment		1,595,517
PPP loans receivable
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	74,420
Bank Overdrafts
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,127
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,801,792	1,748,189
Financing Receivable, Allowance for Credit Loss	(25,466)	(23,480)	(10,229)	(9,768)
Interest Receivable		6,017
Loans and Leases Receivable, Recorded Investment		1,754,206
Construction Real Estate Remaining Commercial [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	214,561	226,991
Interest Receivable		572
Loans and Leases Receivable, Recorded Investment		227,563
Construction Real Estate Retail
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	107,225	116,430
Interest Receivable		235
Loans and Leases Receivable, Recorded Investment		116,665
Residential Real Estate Commercial [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	533,802	526,222
Interest Receivable		1,161
Loans and Leases Receivable, Recorded Investment		527,383
Residential Real Estate Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,033,658	1,096,358
Interest Receivable		947
Loans and Leases Receivable, Recorded Investment		1,097,305
Residential Real Estate Home Equity Line Of Credit [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	165,605	182,028
Interest Receivable		647
Loans and Leases Receivable, Recorded Investment		182,675
Residential Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,642	8,436
Interest Receivable		22
Loans and Leases Receivable, Recorded Investment		8,458
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,689,679	1,659,704
Financing Receivable, Allowance for Credit Loss	(26,286)	(17,418)	(12,211)	(11,773)
Interest Receivable		4,510
Loans and Leases Receivable, Recorded Investment		1,664,214
Finance Leases Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	20,532	24,438
Financing Receivable, Allowance for Credit Loss	(238)	(518)	$ (115)	$ 0
Interest Receivable		14
Loans and Leases Receivable, Recorded Investment		$ 24,452
GFSC loans
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,793
Check Loans
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,093
consumer less GFSC and check loans
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,685,793
commercial financial agricultural less PPP and overdraft
Financing Receivable, Impaired [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,223,079