ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY INFORMATION - Analysis of Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending Loan Balances	$ 59,941	$ 62,106
Loans with No Related Reserve	34,491	32,172
Loans with Related Reserve	25,450	29,934
Related Reserve	3,787	5,017
Contractual Principal Balances	79,756	78,982
Average Loan Balances	62,751	60,743
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending Loan Balances	18,592	20,842
Loans with No Related Reserve	3,038	3,422
Loans with Related Reserve	15,554	17,420
Related Reserve	2,806	3,861
Contractual Principal Balances	24,842	23,815
Average Loan Balances	17,941	15,072
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending Loan Balances	13,261	14,181
Loans with No Related Reserve	8,195	8,282
Loans with Related Reserve	5,066	5,899
Related Reserve	679	796
Contractual Principal Balances	15,992	17,015
Average Loan Balances	14,334	14,533
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending Loan Balances	7,911	7,819
Loans with No Related Reserve	6,480	6,304
Loans with Related Reserve	1,431	1,515
Related Reserve	194	203
Contractual Principal Balances	8,953	8,977
Average Loan Balances	8,136	8,158
Owner-occupied commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending Loan Balances	6,032	5,374
Loans with No Related Reserve	4,342	3,654
Loans with Related Reserve	1,690	1,720
Related Reserve	12	12
Contractual Principal Balances	6,360	5,717
Average Loan Balances	6,103	5,827
Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending Loan Balances	7,427	7,598
Loans with No Related Reserve	5,946	4,487
Loans with Related Reserve	1,481	3,111
Related Reserve	89	112
Contractual Principal Balances	16,370	16,658
Average Loan Balances	11,103	12,630
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending Loan Balances	6,718	6,292
Loans with No Related Reserve	6,490	6,023
Loans with Related Reserve	228	269
Related Reserve	7	33
Contractual Principal Balances	7,239	6,800
Average Loan Balances	$ 5,134	$ 4,523