Purchased Loans - Summary of Purchased Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Summary of loans
Gross loans	$ 10,313,459	$ 10,020,914	$ 10,688,408
Commercial, financial, agricultural
Summary of loans
Gross loans	1,445,607		2,249,287
Real estate – construction:
Summary of loans
Gross loans	1,222,052		955,918
Real estate – 1-4 family mortgage:
Summary of loans
Gross loans	2,840,979		2,686,061
Real estate – commercial mortgage:
Summary of loans
Gross loans	4,577,864		4,549,027
Installment loans to individuals
Summary of loans
Gross loans	137,115		$ 172,859
Purchased loans
Summary of loans
Gross loans	974,569	1,009,903
Purchased loans | Commercial, financial, agricultural
Summary of loans
Gross loans	109,368	90,308
Purchased loans | Real estate – construction:
Summary of loans
Gross loans	5,124	4,994
Purchased loans | Real estate – construction: | Residential
Summary of loans
Gross loans	1,259	1,287
Purchased loans | Real estate – construction: | Commercial
Summary of loans
Gross loans	3,865	3,707
Purchased loans | Real estate – 1-4 family mortgage:
Summary of loans
Gross loans	196,392	215,773
Purchased loans | Real estate – 1-4 family mortgage: | Primary
Summary of loans
Gross loans	122,063	134,070
Purchased loans | Real estate – 1-4 family mortgage: | Home equity
Summary of loans
Gross loans	46,239	51,496
Purchased loans | Real estate – 1-4 family mortgage: | Rental/investment
Summary of loans
Gross loans	18,694	20,229
Purchased loans | Real estate – 1-4 family mortgage: | Land development
Summary of loans
Gross loans	9,396	9,978
Purchased loans | Real estate – commercial mortgage:
Summary of loans
Gross loans	632,324	663,053
Purchased loans | Real estate – commercial mortgage: | Land development
Summary of loans
Gross loans	15,942	18,344
Purchased loans | Real estate – commercial mortgage: | Owner-occupied
Summary of loans
Gross loans	220,247	234,132
Purchased loans | Real estate – commercial mortgage: | Non-owner occupied
Summary of loans
Gross loans	396,135	410,577
Purchased loans | Real estate – commercial mortgage: | Land development
Summary of loans
Gross loans	15,942	18,344
Purchased loans | Installment loans to individuals
Summary of loans
Gross loans	$ 31,361	$ 35,775