EMPLOYEE BENEFIT PLANS (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2017 USD ($) Portfolio Fund Participants shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)
Expected Future Benefit Payments [Abstract]
Proceeds from the sales of trading securities		$ 4,629	$ 3,648	$ 1,340
Tax benefit from market valuation adjustment on distribution of BMP ESOP shares			717
Trading Securities [Member]
Expected Future Benefit Payments [Abstract]
Proceeds from the sales of trading securities		4,629	3,648	1,340
Employee Retirement Plan [Member]
Funded Status [Abstract]
Accumulated benefit obligation at end of period		26,029	25,297
Reconciliation of Projected benefit obligation [Roll Forward]
Projected benefit obligation at beginning of period		25,297	25,396
Interest cost		936	979	998
Actuarial (gain) loss		1,284	215
Benefit payments		(1,488)	(1,293)
Projected benefit obligation at end of period		26,029	25,297	25,396
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		23,355	22,676
Return on plan assets		3,477	1,957
Contributions		17	15
Benefit payments		(1,488)	(1,293)
Balance at end of period		25,361	23,355	22,676
Funded status at end of year		(668)	(1,942)
Net Periodic Cost [Abstract]
Interest cost		936	979	998
Expected return on plan assets		(1,579)	(1,532)	(1,656)
Amortization of unrealized loss		1,287	1,551	1,677
Net periodic (credit) cost		644	998	1,019
Change in Accumulated Other Comprehensive Income (Loss) [Abstract]
Balance at beginning of period		(10,240)	(12,001)
Amortization of unrealized loss		1,287	1,551	1,677
Gain (loss) recognized during the year		613	210
Balance at the end of the period		(8,340)	(10,240)	$ (12,001)
Period end component of accumulated other comprehensive loss, net of tax		$ 5,610	$ 5,613
Assumptions Used in Calculations [Abstract]
Discount rate used for net periodic cost		3.82%	3.98%	3.72%
Discount rate used to determine benefit obligation at period end		3.38%	3.82%	3.98%
Expected long-term return on plan assets used for net periodic cost		7.00%	7.00%	7.00%
Expected long-term return on plan assets used to determine benefit obligation at period end		7.00%	7.00%	7.00%
Number of diversified investment portfolios | Portfolio		2
Percentage variance from the target allocation		10.00%
Number of registered mutual funds in LTGE diversified portfolio | Fund		6
Number of common collective trust funds in Long-Term Growth Equity diversified portfolio | Fund		7
Number of intermediate-term bond in Long-Term Growth Equity diversified portfolio | Fund		4
Weighted average allocation by asset category of the assets [Abstract]
Weighted average allocation by asset		100.00%	100.00%
Expected rate of return		7.00%	7.00%
Long-term inflation rate		2.50%
Expected contributions in the fiscal year		$ 17
Actuarial losses anticipated to be recognized as a component of net periodic cost		17
Expected Future Benefit Payments [Abstract]
2018		1,626
2019		1,616
2020		1,598
2021		1,576
2022		1,559
2023 to 2027		7,523
Bank contribution benefit payments		$ 17	$ 15
Employee Retirement Plan [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Eligibility age		21 years
Eligibility service period		1 year
Employee Retirement Plan [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		$ 23,355
Balance at end of period		$ 25,361	$ 23,355
Employee Retirement Plan [Member] | Equity Securities [Member]
Assumptions Used in Calculations [Abstract]
Asset allocations target		66.00%
Weighted average allocation by asset category of the assets [Abstract]
Weighted average allocation by asset		66.00%	62.00%
Employee Retirement Plan [Member] | Equity Securities [Member] | Minimum [Member]
Weighted average allocation by asset category of the assets [Abstract]
Expected rate of return		1.00%
Employee Retirement Plan [Member] | Equity Securities [Member] | Maximum [Member]
Weighted average allocation by asset category of the assets [Abstract]
Expected rate of return		10.00%
Employee Retirement Plan [Member] | Debt Securities (Bond Mutual Fund) [Member]
Assumptions Used in Calculations [Abstract]
Asset allocations target		32.00%
Weighted average allocation by asset category of the assets [Abstract]
Weighted average allocation by asset		32.00%	36.00%
Employee Retirement Plan [Member] | Domestic Large Cap, Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		$ 2,627
Balance at end of period		3,228	$ 2,627
Employee Retirement Plan [Member] | Domestic Large Cap, Mutual Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Large Cap, Mutual Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Large Cap, Mutual Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		2,627
Balance at end of period		3,228	2,627
Employee Retirement Plan [Member] | Domestic Mid Cap, Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		1,189
Balance at end of period		1,344	1,189
Employee Retirement Plan [Member] | Domestic Mid Cap, Mutual Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Mid Cap, Mutual Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Mid Cap, Mutual Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		1,189
Balance at end of period		1,344	1,189
Employee Retirement Plan [Member] | Domestic Small Cap, Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		485
Balance at end of period		513	485
Employee Retirement Plan [Member] | Domestic Small Cap, Mutual Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Small Cap, Mutual Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Small Cap, Mutual Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		485
Balance at end of period		513	485
Employee Retirement Plan [Member] | International Equity, Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		2,657
Balance at end of period		3,198	2,657
Employee Retirement Plan [Member] | International Equity, Mutual Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | International Equity, Mutual Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | International Equity, Mutual Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		2,657
Balance at end of period		$ 3,198	2,657
Employee Retirement Plan [Member] | Fixed Income, Mutual Fund [Member] | Minimum [Member]
Weighted average allocation by asset category of the assets [Abstract]
Expected rate of return		0.00%
Employee Retirement Plan [Member] | Fixed Income, Mutual Fund [Member] | Maximum [Member]
Weighted average allocation by asset category of the assets [Abstract]
Expected rate of return		6.00%
Employee Retirement Plan [Member] | Fixed Income, Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		$ 8,408
Balance at end of period		8,133	8,408
Employee Retirement Plan [Member] | Fixed Income, Mutual Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Fixed Income, Mutual Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Fixed Income, Mutual Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		8,408
Balance at end of period		$ 8,133	$ 8,408
Employee Retirement Plan [Member] | Cash Equivalents, Mutual Fund [Member]
Assumptions Used in Calculations [Abstract]
Asset allocations target		2.00%
Weighted average allocation by asset category of the assets [Abstract]
Weighted average allocation by asset		2.00%	2.00%
Employee Retirement Plan [Member] | Cash Equivalents, Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		$ 366
Balance at end of period		510	$ 366
Employee Retirement Plan [Member] | Cash Equivalents, Mutual Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Cash Equivalents, Mutual Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Cash Equivalents, Mutual Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		366
Balance at end of period		510	366
Employee Retirement Plan [Member] | Domestic Large Cap, Common Collective Investment Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Large Cap, Common Collective Investment Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		4,784
Balance at end of period		5,246	4,784
Employee Retirement Plan [Member] | Domestic Large Cap, Common Collective Investment Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Large Cap, Common Collective Investment Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		4,784
Balance at end of period		5,246	4,784
Employee Retirement Plan [Member] | Domestic Mid Cap, Common Collective Trust Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Mid Cap, Common Collective Trust Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		638
Balance at end of period		702	638
Employee Retirement Plan [Member] | Domestic Mid Cap, Common Collective Trust Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Mid Cap, Common Collective Trust Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		638
Balance at end of period		702	638
Employee Retirement Plan [Member] | Domestic Small Cap, Common Collective Trust Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Small Cap, Common Collective Trust Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		1,405
Balance at end of period		1,527	1,405
Employee Retirement Plan [Member] | Domestic Small Cap, Common Collective Trust Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | Domestic Small Cap, Common Collective Trust Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		1,405
Balance at end of period		1,527	1,405
Employee Retirement Plan [Member] | International Equity, Common Collective Trust Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | International Equity, Common Collective Trust Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		796
Balance at end of period		960	796
Employee Retirement Plan [Member] | International Equity, Common Collective Trust Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0
Balance at end of period		0	0
Employee Retirement Plan [Member] | International Equity, Common Collective Trust Fund [Member] | Fair Value [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		796
Balance at end of period		960	796
BMP and the Director Retirement Plan [Member]
Funded Status [Abstract]
Accumulated benefit obligation at end of period		10,364	11,351
Reconciliation of Projected benefit obligation [Roll Forward]
Projected benefit obligation at beginning of period		11,351	11,062
Interest cost		379	392	$ 375
Actuarial (gain) loss		(822)	131
Benefit payments		(544)	(234)
Projected benefit obligation at end of period		10,364	11,351	11,062
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0	0
Contributions		544	234
Benefit payments		(544)	(234)
Balance at end of period		0	0	0
Funded status at end of year		(10,364)	(11,351)
Net Periodic Cost [Abstract]
Interest cost		379	392	375
Amortization of unrealized loss		147	161	242
Net periodic (credit) cost		526	553	617
Change in Accumulated Other Comprehensive Income (Loss) [Abstract]
Balance at beginning of period		(2,758)	(2,788)
Amortization of unrealized loss		147	161	242
Gain (loss) recognized during the year		822	(131)
Balance at the end of the period		(1,789)	(2,758)	(2,788)
Period end component of accumulated other comprehensive loss, net of tax		1,203	1,512
Expected Future Benefit Payments [Abstract]
2018		789
2019		786
2020		815
2021		807
2022		798
2023 to 2027		3,923
Bank contribution benefit payments		544	234
Postretirement Benefit Plan [Member]
Funded Status [Abstract]
Accumulated benefit obligation at end of period		1,768	1,756
Reconciliation of Projected benefit obligation [Roll Forward]
Projected benefit obligation at beginning of period		1,756	1,825
Interest cost		59	63	94
Actuarial (gain) loss		132	(10)
Benefit payments		(179)	(122)
Projected benefit obligation at end of period		1,768	1,756	1,825
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Balance at beginning of period		0	0
Contributions		179	122
Benefit payments		(179)	(122)
Balance at end of period		0	0	0
Funded Status [Abstract]
Deficiency of plan assets over projected benefit obligation and accrued expense included in other liabilities		(1,768)	(1,756)
Net Periodic Cost [Abstract]
Service cost		0	0	9
Interest cost		59	63	94
Curtailment gain	[1]	0	0	(3,394)
Amortization of unrealized loss		(14)	(12)	(19)
Net periodic (credit) cost		45	51	(3,310)
Change in Accumulated Other Comprehensive Income (Loss) [Abstract]
Balance at beginning of period		349	351
Amortization of unrealized loss		(14)	(12)	(19)
Gain (loss) recognized during the year		(132)	10
Balance at the end of the period		203	349	$ 351
Period end component of accumulated other comprehensive loss, net of tax		$ (137)	$ (191)
Assumptions Used in Calculations [Abstract]
Discount rate used for net periodic cost		3.48%	3.58%	3.80%
Rate of increase in compensation levels used for net periodic cost				3.50%
Discount rate used to determine benefit obligation at period end		3.16%	3.48%	3.58%
Rate of increase in compensation levels used to determine benefit obligation at period end				3.50%
Expected Future Benefit Payments [Abstract]
2018		$ 121
2019		116
2020		107
2021		101
2022		94
2023 to 2027		347
Bank contribution benefit payments		179	$ 122
Assumed Medical Care Cost Trend Rates [Abstract]
Increase the net periodic cost from an escalation in the assumed medical care cost trend rates by 1% in each year		1
Decrease the net periodic cost from a decline in the assumed medical care cost trend rates by 1% in each year		$ 1
Health care cost trend rate assumed for next fiscal year		6.50%
Ultimate health care cost trend rate		5.00%
Effect of one percentage point increase on accumulated postretirement benefit obligation		$ 28
Reduction in the accumulated Postretirement Benefit Plan obligation that would result from a decline in the assumed medical care cost trend rates by 1% in each year		26
Director Retirement Plan [Member]
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Contributions		$ 201
Assumptions Used in Calculations [Abstract]
Discount rate used for net periodic cost		3.53%	3.67%	3.49%
Discount rate used to determine benefit obligation at period end		3.17%	3.53%	3.67%
Weighted average allocation by asset category of the assets [Abstract]
Expected contributions in the fiscal year		$ 226
Actuarial losses anticipated to be recognized as a component of net periodic cost		$ 75
Expected Future Benefit Payments [Abstract]
Age of eligibility for outside director		75 years
Bank contribution benefit payments		$ 201
Defined contribution costs recognized		0
BMP [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment in holding company's common stock		5,018	$ 11,981
Plan assets at fair value (investments in trust funds managed by trustee) [Roll Forward]
Contributions		$ 343
Assumptions Used in Calculations [Abstract]
Discount rate used for net periodic cost		3.46%	3.54%	3.39%
Discount rate used to determine benefit obligation at period end		3.13%	3.46%	3.54%
Weighted average allocation by asset category of the assets [Abstract]
Expected contributions in the fiscal year		$ 564
Actuarial losses anticipated to be recognized as a component of net periodic cost		34
Expected Future Benefit Payments [Abstract]
Bank contribution benefit payments		$ 343
Number of participants that elected lump-sum distribution | Participants		3
Lump-sum distribution for retired participant		$ 11,828	$ 7,736
Distribution of common stock (in shares) | shares		365,104	239,822
Component held by ESOP		$ 7,151	$ 4,088
Tax benefit from market valuation adjustment on distribution of BMP ESOP shares		1,454	717
Defined contribution costs recognized		336	744	$ 1,900
BMP [Member] | Trading Securities [Member]
Expected Future Benefit Payments [Abstract]
Proceeds from the sales of trading securities		$ 4,629	$ 3,648

[1] The Postretirement Plan was amended effective March 31, 2015, whereby post-amendment retirees are not eligible to participate in the plan. The amendment resulted in a curtailment gain.