CREDIT QUALITY ASSESSMENT (Summary of Impaired Loans) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Credit Quality Assessment [Abstract]
Impaired loans with a specific allowance	$ 11,693	$ 13,563	$ 14,208
Impaired loans without a specific allowance	9,116	10,529	14,719
Total impaired loans	20,809	24,092	28,927
Allowance for loan and lease losses related to impaired loans	4,014	4,825	3,375
Allowance for loan and lease losses related to loans collectively evaluated	41,243	39,242	37,520
Total allowance for loan and lease losses	45,257	44,067	40,895
Average impaired loans for the period	23,179	26,382	29,828
Contractual interest income due on impaired loans during the period	2,314	2,082	2,527
Interest income on impaired loans recognized on a cash basis	754	511	961
Interest income on impaired loans recognized on an accrual basis	$ 169	$ 186	$ 274