Loans and Allowance for Credit Losses - Outstanding Balances of Loan (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 6,839,230	$ 6,761,183	$ 6,189,148
Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,173,452	1,555,986
Commercial, financial, agricultural and other [Member] | Time and demand loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,159,524	1,541,382
Commercial, financial, agricultural and other [Member] | Commercial credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	13,928	14,604
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	494,456	427,221
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,920,250	1,750,592
Residential Real Estate [Member] | Senior Lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,299,534	1,144,323
Residential Real Estate [Member] | Junior Lien
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	620,716	606,269
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,251,097	2,211,569
Commercial real estate [Member] | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	385,432	371,239
Commercial real estate [Member] | Nonowner Occupied Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,465,247	1,421,151
Commercial real estate [Member] | Owner Occupied Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	400,418	419,179
Loans To Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	999,975	815,815
Loans To Individuals [Member] | Automobile Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	901,280	712,800
Loans To Individuals [Member] | Consumer Credit Cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	11,151	12,360
Loans To Individuals [Member] | Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 87,544	$ 90,655