Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Summary of loans, by loan type
Total loans	$ 7,024,380	$ 6,894,946
Commercial, financial and agricultural
Summary of loans, by loan type
Total loans	3,504,826	3,379,837
Real estate - mortgage
Summary of loans, by loan type
Total loans	1,118,192	1,140,377
Real estate - construction
Summary of loans, by loan type
Total loans	2,216,740	2,185,883
Consumer
Summary of loans, by loan type
Total loans	45,440	47,800
Foreign
Summary of loans, by loan type
Total loans	$ 139,182	$ 141,049