Loans and Leases - Allowance for Credit Losses, Loans and Leases, Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 68,286	$ 71,497	$ 71,924	$ 83,044
Provision (reversal of provision) for credit losses	5,440	101	1,878	(11,158)
Charge-offs	(1,775)	(1,141)	(2,123)	(1,626)
Recoveries	(60)	(898)	(332)	(1,095)
Ending balance	72,011	71,355	72,011	71,355
Commercial Financial And Agricultural [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,840	10,233	13,536	13,584
Provision (reversal of provision) for credit losses	1,123	1,689	(548)	(1,389)
Charge-offs	0	(350)	(214)	(688)
Recoveries	(41)	(162)	(230)	(227)
Ending balance	13,004	11,734	13,004	11,734
Paycheck Protection Program Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1	0	2	0
Provision (reversal of provision) for credit losses	(1)	3	(2)	3
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	0	3	0	3
Real-Estate Commercial [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	40,426	45,459	41,095	52,230
Provision (reversal of provision) for credit losses	2,942	(2,347)	2,273	(9,118)
Charge-offs	(1,690)	(523)	(1,690)	(523)
Recoveries	0	(605)	0	(605)
Ending balance	41,678	43,194	41,678	43,194
Real-Estate Construction [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,634	2,799	4,575	3,298
Provision (reversal of provision) for credit losses	589	850	(352)	351
Charge-offs	0		0	0
Recoveries	0		0	0
Ending balance	4,223	3,649	4,223	3,649
Real Estate Residential Secured For Business Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,202	6,692	6,482	7,317
Provision (reversal of provision) for credit losses	215	260	(113)	(419)
Charge-offs	0	(227)	0	(227)
Recoveries	(3)	(22)	(51)	(76)
Ending balance	6,420	6,747	6,420	6,747
Real Estate Residential Secured For Personal Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,592	3,056	2,403	3,055
Provision (reversal of provision) for credit losses	345	(436)	534	(435)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	2,937	2,620	2,937	2,620
Real Estate Home Equity Secured For Personal Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	976	1,257	1,028	1,176
Provision (reversal of provision) for credit losses	110	(155)	57	(76)
Charge-offs	0		0	0
Recoveries	(12)	(22)	(11)	(24)
Ending balance	1,074	1,124	1,074	1,124
Loans to Individuals [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	369	447	363	533
Provision (reversal of provision) for credit losses	14	(145)	71	(203)
Charge-offs	(27)	(23)	(102)	(79)
Recoveries	(20)	(40)	(44)	(68)
Ending balance	376	319	376	319
Lease Financings [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,246	1,404	2,290	1,701
Provision (reversal of provision) for credit losses	103	382	108	128
Charge-offs	(58)	(18)	(117)	(109)
Recoveries	(8)	(47)	(18)	(95)
Ending balance	2,299	1,815	2,299	1,815
Unallocated [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	150	150	150
Provision (reversal of provision) for credit losses	0	0	(150)	0
Ending balance	$ 0	$ 150	$ 0	$ 150