CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 724,345	$ 687,336
Other comprehensive (loss) income before reclassifications	(12,592)	1,160
Less: Amounts reclassified from accumulated other comprehensive (loss) income	(76)	(330)
Net current-period other comprehensive income (loss)	(12,668)	830
Ending Balance	746,279	704,001
Net change in investment securities available for sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(7,842)	(8,194)
Other comprehensive (loss) income before reclassifications	(11,827)	1,272
Less: Amounts reclassified from accumulated other comprehensive (loss) income	(16)	(206)
Net current-period other comprehensive income (loss)	(11,843)	1,066
Ending Balance	(19,685)	(7,128)
Net change in securities held to maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	1,223	1,392
Other comprehensive (loss) income before reclassifications	0	0
Less: Amounts reclassified from accumulated other comprehensive (loss) income	(119)	(101)
Net current-period other comprehensive income (loss)	(119)	(101)
Ending Balance	1,104	1,291
Net change in defined benefit plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	865	957
Other comprehensive (loss) income before reclassifications	0	0
Less: Amounts reclassified from accumulated other comprehensive (loss) income	59	(23)
Net current-period other comprehensive income (loss)	59	(23)
Ending Balance	924	934
Net change in fair value of derivative used for cash flow hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(2,398)	(1,772)
Other comprehensive (loss) income before reclassifications	(765)	(112)
Less: Amounts reclassified from accumulated other comprehensive (loss) income	0	0
Net current-period other comprehensive income (loss)	(765)	(112)
Ending Balance	(3,163)	(1,884)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(8,152)	(7,617)
Ending Balance	$ (20,820)	$ (6,787)