Loans Schedule of average recorded investment and interest income recognized on loans individually evaluated for impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 108,455	$ 77,491	$ 48,144
Impaired Financing Receivable, Average Recorded Investment	92,294	57,768	51,041
Impaired Financing Receivable, Interest Income, Cash Basis Method	2,879	1,893	1,890
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	28,836	33,088	15,120
Impaired Financing Receivable, Average Recorded Investment	30,280	21,415	21,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	735	527	695
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	70,357	41,791	28,426
Impaired Financing Receivable, Average Recorded Investment	55,279	32,132	23,024
Impaired Financing Receivable, Interest Income, Cash Basis Method	1,890	1,241	1,047
Construction Real Estate Remaining Commercial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	3,110	453	1,866
Impaired Financing Receivable, Average Recorded Investment	1,291	1,987	1,709
Impaired Financing Receivable, Interest Income, Cash Basis Method	50	26	34
Residential Real Estate Commercial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	4,557	2,025	2,732
Impaired Financing Receivable, Average Recorded Investment	4,329	2,175	5,308
Impaired Financing Receivable, Interest Income, Cash Basis Method	204	99	$ 114
Leases
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	1,595	134
Impaired Financing Receivable, Average Recorded Investment	$ 1,115	$ 59