Non Purchased Loans - Loan Portfolio Not Subject to Risk Rating (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Loan portfolio not subject to risk rating
Loans, net of unearned income	$ 10,020,914	$ 10,933,647
Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Loans, net of unearned income	1,423,270	2,536,984
Lease financing
Loan portfolio not subject to risk rating
Loans, net of unearned income	76,125	75,862
Real estate – construction:
Loan portfolio not subject to risk rating
Loans, net of unearned income	1,104,896	858,104
Real estate – 1-4 family mortgage:
Loan portfolio not subject to risk rating
Loans, net of unearned income	2,724,246	2,698,308
Real estate – commercial mortgage
Loan portfolio not subject to risk rating
Loans, net of unearned income	4,549,037	4,554,852
Installment loans to individuals
Loan portfolio not subject to risk rating
Loans, net of unearned income	143,340	209,537
Non purchased loans and leases
Loan portfolio not subject to risk rating
Loans, net of unearned income	$ 9,011,011	$ 9,419,540