Loans - Summary of Nonaccrual Status Loans (Details) - Non-Covered - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 47,012	$ 35,358
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	13,817	14,152
Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	2,352	1,857
Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	26,323	12,941
Commercial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	11,314	8,488
SBA | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	2,503	5,664
Construction | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	4,520	6,408
Indirect automobile | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	1,912	1,276
Installment | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	440	581
Residential mortgage | Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	23,169	10,860
Home equity lines of credit | Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 3,154	$ 2,081