CREDIT QUALITY ASSESSMENT (Activity in Allowance for Loan and Lease Losses by Respective Loan Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 44,067	$ 40,895	$ 40,895
Provision (credit)	194	1,236	5,546
Charge-offs	(482)	(511)	(3,134)
Recoveries	82	146	760
Net charge-offs	(400)	(365)	(2,374)
Balance at period end	43,861	41,766	44,067
Total loans and leases	$ 3,992,996		$ 3,927,808
Allowance for loans and leases to total loans and leases ratio	1.10%		1.12%
Balance of loans specifically evaluated for impairment	$ 23,878		$ 24,092
Allowance for loans specifically evaluated for impairment	$ 5,318		$ 4,825
Specific allowance to specific loans ratio	22.27%		20.03%
Balance of loans collectively evaluated	$ 3,969,118		$ 3,903,716
Allowance for loans collectively evaluated	$ 38,543		$ 39,242
Collective allowance to collective loans ratio	0.97%		1.01%
Commercial
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 7,539	6,529	$ 6,529
Provision (credit)	400		1,563
Charge-offs	(289)		(597)
Recoveries	29		44
Net charge-offs	(260)		(553)
Balance at period end	7,679		7,539
Total loans and leases	$ 457,216		$ 467,286
Allowance for loans and leases to total loans and leases ratio	1.68%		1.61%
Balance of loans specifically evaluated for impairment	$ 7,012		$ 7,018
Allowance for loans specifically evaluated for impairment	$ 3,014		$ 2,604
Specific allowance to specific loans ratio	42.98%		37.10%
Balance of loans collectively evaluated	$ 450,204		$ 460,268
Allowance for loans collectively evaluated	$ 4,665		$ 4,935
Collective allowance to collective loans ratio	1.04%		1.07%
Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 2,828	3,456	$ 3,456
Provision (credit)	365		112
Charge-offs	(191)		(888)
Recoveries	24		148
Net charge-offs	(167)		(740)
Balance at period end	3,026		2,828
Total loans and leases	$ 455,478		$ 456,657
Allowance for loans and leases to total loans and leases ratio	0.66%		0.62%
Balance of loans collectively evaluated	$ 455,478		$ 456,657
Allowance for loans collectively evaluated	$ 3,026		$ 2,828
Collective allowance to collective loans ratio	0.66%		0.62%
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 4,652	4,691	$ 4,691
Provision (credit)	(433)		(31)
Charge-offs	0		(48)
Recoveries	0		40
Net charge-offs	0		(8)
Balance at period end	4,219		4,652
Total loans and leases	$ 309,350		$ 308,279
Allowance for loans and leases to total loans and leases ratio	1.36%		1.51%
Balance of loans specifically evaluated for impairment	$ 137		$ 137
Allowance for loans specifically evaluated for impairment	$ 0		$ 0
Specific allowance to specific loans ratio	0.00%		0.00%
Balance of loans collectively evaluated	$ 309,213		$ 308,142
Allowance for loans collectively evaluated	$ 4,219		$ 4,652
Collective allowance to collective loans ratio	1.36%		1.51%
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 12,939	10,440	$ 10,440
Provision (credit)	(42)		2,563
Charge-offs	0		(197)
Recoveries	5		133
Net charge-offs	5		(64)
Balance at period end	12,902		12,939
Total loans and leases	$ 979,410		$ 928,113
Allowance for loans and leases to total loans and leases ratio	1.32%		1.39%
Balance of loans specifically evaluated for impairment	$ 7,970		$ 8,107
Allowance for loans specifically evaluated for impairment	$ 1,736		$ 1,736
Specific allowance to specific loans ratio	21.78%		21.41%
Balance of loans collectively evaluated	$ 971,440		$ 920,006
Allowance for loans collectively evaluated	$ 11,166		$ 11,203
Collective allowance to collective loans ratio	1.15%		1.22%
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 7,885	7,984	$ 7,984
Provision (credit)	(805)		(104)
Charge-offs	0		0
Recoveries	0		5
Net charge-offs	0		5
Balance at period end	7,080		7,885
Total loans and leases	$ 772,443		$ 775,552
Allowance for loans and leases to total loans and leases ratio	0.92%		1.02%
Balance of loans specifically evaluated for impairment	$ 5,849		$ 5,567
Allowance for loans specifically evaluated for impairment	$ 568		$ 485
Specific allowance to specific loans ratio	9.71%		8.71%
Balance of loans collectively evaluated	$ 766,594		$ 769,985
Allowance for loans collectively evaluated	$ 6,512		$ 7,400
Collective allowance to collective loans ratio	0.85%		0.96%
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 7,261	6,901	$ 6,901
Provision (credit)	529		1,406
Charge-offs	(2)		(1,404)
Recoveries	18		358
Net charge-offs	16		(1,046)
Balance at period end	7,806		7,261
Total loans and leases	$ 848,814		$ 841,692
Allowance for loans and leases to total loans and leases ratio	0.92%		0.86%
Balance of loans specifically evaluated for impairment	$ 2,910		$ 3,263
Allowance for loans specifically evaluated for impairment	0		0
Balance of loans collectively evaluated	845,904		838,429
Allowance for loans collectively evaluated	$ 7,806		$ 7,261
Collective allowance to collective loans ratio	0.92%		0.87%
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 963	$ 894	$ 894
Provision (credit)	180		37
Charge-offs	0		0
Recoveries	6		32
Net charge-offs	6		32
Balance at period end	1,149		963
Total loans and leases	$ 170,285		$ 150,229
Allowance for loans and leases to total loans and leases ratio	0.67%		0.64%
Balance of loans specifically evaluated for impairment	$ 0		$ 0
Allowance for loans specifically evaluated for impairment	0		0
Balance of loans collectively evaluated	170,285		150,229
Allowance for loans collectively evaluated	$ 1,149		$ 963
Collective allowance to collective loans ratio	0.67%		0.64%