Non Purchased Loans - Loan Portfolio Not Subject to Risk Rating (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Loan portfolio not subject to risk rating
Total loans, net of unearned income	$ 11,000,796	$ 9,693,463
Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total loans, net of unearned income	2,641,598	1,367,972
Lease financing
Loan portfolio not subject to risk rating
Total loans, net of unearned income	84,271	85,700
Real estate – construction:
Loan portfolio not subject to risk rating
Total loans, net of unearned income	791,108	826,483
Real estate – 1-4 family mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income	2,788,513	2,866,613
Real estate – commercial mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income	4,410,753	4,244,265
Installment loans to individuals
Loan portfolio not subject to risk rating
Total loans, net of unearned income	284,553	302,430
Non purchased loans and leases
Loan portfolio not subject to risk rating
Total loans, net of unearned income	$ 9,206,101	7,587,974
Non purchased loans and leases | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total loans, net of unearned income		2,933,132
Non purchased loans and leases | Performing and Nonperforming | Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total loans, net of unearned income		248,891
Non purchased loans and leases | Performing and Nonperforming | Lease financing
Loan portfolio not subject to risk rating
Total loans, net of unearned income		81,875
Non purchased loans and leases | Performing and Nonperforming | Real estate – construction:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		66,241
Non purchased loans and leases | Performing and Nonperforming | Real estate – 1-4 family mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		2,003,619
Non purchased loans and leases | Performing and Nonperforming | Real estate – commercial mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		332,669
Non purchased loans and leases | Performing and Nonperforming | Installment loans to individuals
Loan portfolio not subject to risk rating
Total loans, net of unearned income		199,837
Non purchased loans and leases | Performing
Loan portfolio not subject to risk rating
Total loans, net of unearned income		2,918,059
Non purchased loans and leases | Performing | Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total loans, net of unearned income		247,575
Non purchased loans and leases | Performing | Lease financing
Loan portfolio not subject to risk rating
Total loans, net of unearned income		81,649
Non purchased loans and leases | Performing | Real estate – construction:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		66,241
Non purchased loans and leases | Performing | Real estate – 1-4 family mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		1,992,331
Non purchased loans and leases | Performing | Real estate – commercial mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		330,714
Non purchased loans and leases | Performing | Installment loans to individuals
Loan portfolio not subject to risk rating
Total loans, net of unearned income		199,549
Non purchased loans and leases | Non- Performing
Loan portfolio not subject to risk rating
Total loans, net of unearned income		15,073
Non purchased loans and leases | Non- Performing | Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total loans, net of unearned income		1,316
Non purchased loans and leases | Non- Performing | Lease financing
Loan portfolio not subject to risk rating
Total loans, net of unearned income		226
Non purchased loans and leases | Non- Performing | Real estate – construction:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		0
Non purchased loans and leases | Non- Performing | Real estate – 1-4 family mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		11,288
Non purchased loans and leases | Non- Performing | Real estate – commercial mortgage:
Loan portfolio not subject to risk rating
Total loans, net of unearned income		1,955
Non purchased loans and leases | Non- Performing | Installment loans to individuals
Loan portfolio not subject to risk rating
Total loans, net of unearned income		$ 288