Non Purchased Loans - Summary of Non-Purchased Loans and Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Summary of loans
Loans, net of unearned income	$ 11,000,796	$ 9,693,463
Commercial, financial, agricultural
Summary of loans
Loans, net of unearned income	2,641,598	1,367,972
Lease financing
Summary of loans
Loans, net of unearned income	84,271	85,700
Real estate – construction:
Summary of loans
Loans, net of unearned income	791,108	826,483
Real estate – construction: | Residential
Summary of loans
Loans, net of unearned income	295,931	289,050
Real estate – construction: | Commercial
Summary of loans
Loans, net of unearned income	495,177	537,433
Real estate – 1-4 family mortgage:
Summary of loans
Loans, net of unearned income	2,788,513	2,866,613
Real estate – 1-4 family mortgage: | Primary
Summary of loans
Loans, net of unearned income	1,756,253	1,781,948
Real estate – 1-4 family mortgage: | Home equity
Summary of loans
Loans, net of unearned income	543,468	573,540
Real estate – 1-4 family mortgage: | Rental/investment
Summary of loans
Loans, net of unearned income	318,803	335,100
Real estate – 1-4 family mortgage: | Land development
Summary of loans
Loans, net of unearned income	169,989	176,025
Real estate – commercial mortgage:
Summary of loans
Loans, net of unearned income	4,410,753	4,244,265
Real estate – commercial mortgage: | Land development
Summary of loans
Loans, net of unearned income	155,766	156,089
Real estate – commercial mortgage: | Owner-occupied
Summary of loans
Loans, net of unearned income	1,660,674	1,637,281
Real estate – commercial mortgage: | Non-owner occupied
Summary of loans
Loans, net of unearned income	2,594,313	2,450,895
Installment loans to individuals
Summary of loans
Loans, net of unearned income	284,553	302,430
Non purchased loans and leases
Summary of loans
Gross loans	9,209,593	7,591,799
Unearned income	(3,492)	(3,825)
Loans, net of unearned income	9,206,101	7,587,974
Non purchased loans and leases | Commercial, financial, agricultural
Summary of loans
Gross loans	2,416,243	1,052,353
Non purchased loans and leases | Lease financing
Summary of loans
Gross loans	84,271	85,700
Non purchased loans and leases | Real estate – construction:
Summary of loans
Gross loans	756,872	774,901
Non purchased loans and leases | Real estate – construction: | Residential
Summary of loans
Gross loans	291,983	272,643
Non purchased loans and leases | Real estate – construction: | Commercial
Summary of loans
Gross loans	464,889	502,258
Non purchased loans and leases | Real estate – 1-4 family mortgage:
Summary of loans
Gross loans	2,342,987	2,350,126
Non purchased loans and leases | Real estate – 1-4 family mortgage: | Primary
Summary of loans
Gross loans	1,476,196	1,449,219
Non purchased loans and leases | Real estate – 1-4 family mortgage: | Home equity
Summary of loans
Gross loans	440,774	456,265
Non purchased loans and leases | Real estate – 1-4 family mortgage: | Rental/investment
Summary of loans
Gross loans	277,647	291,931
Non purchased loans and leases | Real estate – 1-4 family mortgage: | Land development
Summary of loans
Gross loans	148,370	152,711
Non purchased loans and leases | Real estate – commercial mortgage:
Summary of loans
Gross loans	3,400,718	3,128,876
Non purchased loans and leases | Real estate – commercial mortgage: | Land development
Summary of loans
Gross loans	118,777	116,085
Non purchased loans and leases | Real estate – commercial mortgage: | Owner-occupied
Summary of loans
Gross loans	1,270,197	1,209,204
Non purchased loans and leases | Real estate – commercial mortgage: | Non-owner occupied
Summary of loans
Gross loans	2,011,744	1,803,587
Non purchased loans and leases | Installment loans to individuals
Summary of loans
Gross loans	$ 208,502	$ 199,843