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, 2016	Mar. 31, 2015	Dec. 31, 2015
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 40,895	$ 37,802	$ 37,802
Provision (credit)	1,236	597	5,371
Charge-offs	(511)	(1,114)	(3,795)
Recoveries	146	190	1,517
Net charge-offs	(365)	(924)	(2,278)
Balance at period end	41,766	37,475	40,895
Total loans and leases	$ 3,560,688		$ 3,495,370
Allowance for loans and leases to total loans and leases ratio	1.17%		1.17%
Balance of loans specifically evaluated for impairment	$ 29,474		$ 28,927
Allowance for loans specifically evaluated for impairment	$ 3,208		$ 3,375
Specific allowance to specific loans ratio	10.88%		11.67%
Balance of loans collectively evaluated	$ 3,531,214		$ 3,466,443
Allowance for loans collectively evaluated	$ 38,558		$ 37,520
Collective allowance to collective loans ratio	1.09%		1.08%
Commercial
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 6,529	5,852	$ 5,852
Provision (credit)	228		508
Charge-offs	(64)		(306)
Recoveries	(3)		475
Net charge-offs	(67)		169
Balance at period end	6,690		6,529
Total loans and leases	$ 451,239		$ 465,765
Allowance for loans and leases to total loans and leases ratio	1.48%		1.40%
Balance of loans specifically evaluated for impairment	$ 5,078		$ 5,273
Allowance for loans specifically evaluated for impairment	$ 1,354		$ 1,318
Specific allowance to specific loans ratio	26.66%		25.00%
Balance of loans collectively evaluated	$ 446,161		$ 460,492
Allowance for loans collectively evaluated	$ 5,336		$ 5,211
Collective allowance to collective loans ratio	1.20%		1.13%
Leases
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 0	9	$ 9
Provision (credit)	0		(5)
Charge-offs	0		(4)
Recoveries	0		0
Net charge-offs	0		(4)
Balance at period end	0		0
Total loans and leases	0		0
Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	3,456	3,592	3,592
Provision (credit)	(353)		619
Charge-offs	(114)		(998)
Recoveries	60		243
Net charge-offs	(54)		(755)
Balance at period end	3,049		3,456
Total loans and leases	$ 447,198		$ 450,875
Allowance for loans and leases to total loans and leases ratio	0.68%		0.77%
Balance of loans collectively evaluated	$ 447,198		$ 450,875
Allowance for loans collectively evaluated	$ 3,049		$ 3,456
Collective allowance to collective loans ratio	0.68%		0.77%
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 4,691	4,267	$ 4,267
Provision (credit)	44		583
Charge-offs	(48)		(739)
Recoveries	0		580
Net charge-offs	(48)		(159)
Balance at period end	4,687		4,691
Total loans and leases	$ 261,204		$ 255,980
Allowance for loans and leases to total loans and leases ratio	1.79%		1.83%
Balance of loans specifically evaluated for impairment	$ 147		$ 194
Allowance for loans specifically evaluated for impairment	$ 9		$ 58
Specific allowance to specific loans ratio	6.12%		29.90%
Balance of loans collectively evaluated	$ 261,057		$ 255,786
Allowance for loans collectively evaluated	$ 4,678		$ 4,633
Collective allowance to collective loans ratio	1.79%		1.81%
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 10,440	9,784	$ 9,784
Provision (credit)	1,060		727
Charge-offs	(197)		(91)
Recoveries	5		20
Net charge-offs	(192)		(71)
Balance at period end	11,308		10,440
Total loans and leases	$ 783,161		$ 719,084
Allowance for loans and leases to total loans and leases ratio	1.44%		1.45%
Balance of loans specifically evaluated for impairment	$ 9,943		$ 10,441
Allowance for loans specifically evaluated for impairment	$ 1,194		$ 1,489
Specific allowance to specific loans ratio	12.01%		14.26%
Balance of loans collectively evaluated	$ 773,218		$ 708,643
Allowance for loans collectively evaluated	$ 10,114		$ 8,951
Collective allowance to collective loans ratio	1.31%		1.26%
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 7,984	7,143	$ 7,143
Provision (credit)	59		1,881
Charge-offs	0		(1,043)
Recoveries	3		3
Net charge-offs	3		(1,040)
Balance at period end	8,046		7,984
Total loans and leases	$ 675,560		$ 678,027
Allowance for loans and leases to total loans and leases ratio	1.19%		1.18%
Balance of loans specifically evaluated for impairment	$ 7,897		$ 6,580
Allowance for loans specifically evaluated for impairment	$ 651		$ 510
Specific allowance to specific loans ratio	8.24%		7.75%
Balance of loans collectively evaluated	$ 667,663		$ 671,447
Allowance for loans collectively evaluated	$ 7,395		$ 7,474
Collective allowance to collective loans ratio	1.11%		1.11%
Residential Real Estate Portfolio Segment | Residential Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 6,901	6,232	$ 6,232
Provision (credit)	204		1,138
Charge-offs	(88)		(614)
Recoveries	73		145
Net charge-offs	(15)		(469)
Balance at period end	7,090		6,901
Total loans and leases	$ 804,105		$ 796,358
Allowance for loans and leases to total loans and leases ratio	0.88%		0.87%
Balance of loans specifically evaluated for impairment	$ 6,409		$ 6,439
Allowance for loans specifically evaluated for impairment	0		0
Balance of loans collectively evaluated	797,696		789,919
Allowance for loans collectively evaluated	$ 7,090		$ 6,901
Collective allowance to collective loans ratio	0.89%		0.87%
Residential Real Estate Portfolio Segment | Residential Construction
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of year	$ 894	$ 923	$ 923
Provision (credit)	(6)		(80)
Charge-offs	0		0
Recoveries	8		51
Net charge-offs	8		51
Balance at period end	896		894
Total loans and leases	$ 138,221		$ 129,281
Allowance for loans and leases to total loans and leases ratio	0.65%		0.69%
Balance of loans specifically evaluated for impairment	$ 0		$ 0
Allowance for loans specifically evaluated for impairment	0		0
Balance of loans collectively evaluated	138,221		129,281
Allowance for loans collectively evaluated	$ 896		$ 894
Collective allowance to collective loans ratio	0.00%		0.69%