ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY INFORMATION - Schedule of Types of TDR (Detail) - loan	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	6	12
Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	1
Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	1	0
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	1
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	1	2
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	1
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	4	7
Contractual payment reduction and term extension
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	1	0
Contractual payment reduction and term extension | Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Contractual payment reduction and term extension | Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Contractual payment reduction and term extension | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Contractual payment reduction and term extension | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Contractual payment reduction and term extension | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Contractual payment reduction and term extension | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	1	0
Maturity Date Extension
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	3	4
Maturity Date Extension | Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	1
Maturity Date Extension | Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	1	0
Maturity Date Extension | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	1
Maturity Date Extension | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	1	2
Maturity Date Extension | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Maturity Date Extension | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	1	0
Discharged in bankruptcy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	7
Discharged in bankruptcy | Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Discharged in bankruptcy | Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Discharged in bankruptcy | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Discharged in bankruptcy | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Discharged in bankruptcy | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	1
Discharged in bankruptcy | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	6
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	2	1
Other | Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Other | Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Other | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Other | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Other | Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	0	0
Other | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan Modification Total	2	1