CREDIT QUALITY ASSESSMENT (Activity in Allowance for Loan and Lease Losses by Respective Loan Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 53,486	$ 45,257	$ 45,257
Provision (credit) for loan losses	$ 1,524	$ 1,890	3,029	5,620	9,023
Charge-offs			(2,101)	(1,003)	(1,416)
Recoveries			578	535	622
Net charge-offs			(1,523)	(468)	(794)
Balance at period end	54,992	$ 50,409	54,992	50,409	53,486
Total loans and leases	$ 6,596,548		$ 6,596,548		$ 6,571,634
Allowance for loans and leases to total loans and leases ratio	0.83%		0.83%		0.81%
Balance of loans specifically evaluated for impairment	$ 22,046		$ 22,046		$ 22,210
Allowance for loans specifically evaluated for impairment	$ 4,272		$ 4,272		$ 4,924
Specific allowance to specific loans ratio	19.38%		19.38%		22.17%
Balance of loans collectively evaluated	$ 6,561,217		$ 6,561,217		$ 6,523,477
Allowance for loans collectively evaluated	50,720		$ 50,720		$ 48,562
Collective allowance to collective loans ratio			0.77%		0.74%
Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 13,285		$ 25,947
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%
Commercial
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 11,377	8,711	$ 8,711
Provision (credit) for loan losses			(422)		2,857
Charge-offs			(1,176)		(449)
Recoveries			45		258
Net charge-offs			(1,131)		(191)
Balance at period end	9,824		9,824		11,377
Total loans and leases	$ 772,619		$ 772,619		$ 796,264
Allowance for loans and leases to total loans and leases ratio	1.27%		1.27%		1.43%
Balance of loans specifically evaluated for impairment	$ 6,818		$ 6,818		$ 7,586
Allowance for loans specifically evaluated for impairment	$ 2,556		$ 2,556		$ 3,594
Specific allowance to specific loans ratio	37.49%		37.49%		47.38%
Balance of loans collectively evaluated	$ 763,211		$ 763,211		$ 780,523
Allowance for loans collectively evaluated	7,268		$ 7,268		$ 7,783
Collective allowance to collective loans ratio			0.95%		1.00%
Commercial | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 2,590		$ 8,155
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%
Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 2,113	2,383	$ 2,383
Provision (credit) for loan losses			224		203
Charge-offs			(517)		(611)
Recoveries			166		138
Net charge-offs			(351)		(473)
Balance at period end	1,986		1,986		2,113
Total loans and leases	$ 480,530		$ 480,530		$ 517,839
Allowance for loans and leases to total loans and leases ratio	0.41%		0.41%		0.41%
Balance of loans collectively evaluated	$ 479,502		$ 479,502		$ 516,567
Allowance for loans collectively evaluated	1,986		$ 1,986		$ 2,113
Collective allowance to collective loans ratio			0.41%		0.41%
Consumer | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 1,028		$ 1,272
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 5,944	3,501	$ 3,501
Provision (credit) for loan losses			608		2,381
Charge-offs			0		0
Recoveries			228		62
Net charge-offs			228		62
Balance at period end	6,780		6,780		5,944
Total loans and leases	$ 678,906		$ 678,906		$ 681,201
Allowance for loans and leases to total loans and leases ratio	1.00%		1.00%		0.87%
Balance of loans specifically evaluated for impairment	$ 829		$ 829		$ 3,306
Allowance for loans specifically evaluated for impairment	$ 132		$ 132		$ 0
Specific allowance to specific loans ratio	15.92%		15.92%		0.00%
Balance of loans collectively evaluated	$ 678,077		$ 678,077		$ 677,895
Allowance for loans collectively evaluated	6,648		$ 6,648		$ 5,944
Collective allowance to collective loans ratio			0.98%		0.88%
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 0		$ 0
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 17,603	14,970	$ 14,970
Provision (credit) for loan losses			1,892		2,677
Charge-offs			0		(131)
Recoveries			13		87
Net charge-offs			13		(44)
Balance at period end	19,508		19,508		17,603
Total loans and leases	$ 2,036,021		$ 2,036,021		$ 1,958,395
Allowance for loans and leases to total loans and leases ratio	0.96%		0.96%		0.90%
Balance of loans specifically evaluated for impairment	$ 9,229		$ 9,229		$ 5,355
Allowance for loans specifically evaluated for impairment	$ 1,558		$ 1,558		$ 1,207
Specific allowance to specific loans ratio	16.88%		16.88%		22.54%
Balance of loans collectively evaluated	$ 2,017,134		$ 2,017,134		$ 1,938,712
Allowance for loans collectively evaluated	17,950		$ 17,950		$ 16,396
Collective allowance to collective loans ratio			0.89%		0.85%
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 9,658		$ 14,328
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 6,307	7,178	$ 7,178
Provision (credit) for loan losses			148		(871)
Charge-offs			0		0
Recoveries			0		0
Net charge-offs			0		0
Balance at period end	6,455		6,455		6,307
Total loans and leases	$ 1,278,505		$ 1,278,505		$ 1,202,903
Allowance for loans and leases to total loans and leases ratio	0.50%		0.50%		0.52%
Balance of loans specifically evaluated for impairment	$ 3,810		$ 3,810		$ 4,234
Allowance for loans specifically evaluated for impairment	$ 26		$ 26		$ 123
Specific allowance to specific loans ratio	0.68%		0.68%		2.91%
Balance of loans collectively evaluated	$ 1,274,695		$ 1,274,695		$ 1,196,487
Allowance for loans collectively evaluated	6,429		$ 6,429		$ 6,184
Collective allowance to collective loans ratio			0.50%		0.52%
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 0		$ 2,182
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 8,881	$ 7,268	$ 7,268
Provision (credit) for loan losses			834		1,776
Charge-offs			(408)		(225)
Recoveries			120		62
Net charge-offs			(288)		(163)
Balance at period end	9,427		9,427		8,881
Total loans and leases	$ 1,199,275		$ 1,199,275		$ 1,228,247
Allowance for loans and leases to total loans and leases ratio	0.79%		0.79%		0.72%
Balance of loans specifically evaluated for impairment	$ 1,360		$ 1,360		$ 1,729
Allowance for loans specifically evaluated for impairment	$ 0		$ 0		0
Specific allowance to specific loans ratio	0.00%	0.00%	0.00%	0.00%
Balance of loans collectively evaluated	$ 1,197,906		$ 1,197,906		1,226,508
Allowance for loans collectively evaluated	9,427		$ 9,427		$ 8,881
Collective allowance to collective loans ratio			0.79%		0.72%
Residential Real Estate Portfolio Segment | Residential Mortgage | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 9		$ 10
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year			$ 1,261	$ 1,246	$ 1,246
Provision (credit) for loan losses			(255)		0
Charge-offs			0		0
Recoveries			6		15
Net charge-offs			6		15
Balance at period end	1,012		1,012		1,261
Total loans and leases	$ 150,692		$ 150,692		$ 186,785
Allowance for loans and leases to total loans and leases ratio	0.67%		0.67%		0.68%
Balance of loans specifically evaluated for impairment	$ 0		$ 0		$ 0
Allowance for loans specifically evaluated for impairment	$ 0		$ 0		0
Specific allowance to specific loans ratio	0.00%	0.00%	0.00%	0.00%
Balance of loans collectively evaluated	$ 150,692		$ 150,692		186,785
Allowance for loans collectively evaluated	$ 1,012		$ 1,012		$ 1,261
Collective allowance to collective loans ratio			0.67%		0.68%
Residential Real Estate Portfolio Segment | Residential Construction | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance of loans acquired			$ 0		$ 0
Allowance for loans acquired			$ 0		$ 0
Allowance to loans acquired with deteriorated credity quality ratio			0.00%		0.00%