REGULATORY CAPITAL (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Oct. 08, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Subordinated debentures	$ 58,677	$ 58,599	$ 15,000
Capital	$ 351,791	$ 335,740
Capital to Risk Weighted Assets	12.94%	12.98%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.625%	8.00%
Tier One Risk Based Capital	$ 313,052	$ 299,552
Tier One Risk Based Capital to Risk Weighted Assets	11.51%	11.58%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.625%	6.00%
Common equity tier I capital	$ 278,673	$ 269,350
Common Equity Tier I Risk Based Capital Ratio	10.25%	10.42%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	5.125%	4.50%
Tier One Leverage Capital	$ 313,052	$ 299,552
Excess Tier One Leverage Capital to Average Assets	8.44%	8.74%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Acadia Trust [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier One Risk Based Capital Required for Capital Adequacy	$ 2,500
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	$ 317,484	$ 304,847
Capital to Risk Weighted Assets	11.64%	11.75%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.625%	8.00%
Tier One Risk Based Capital	$ 293,745	$ 283,659
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier One Risk Based Capital to Risk Weighted Assets	10.77%	10.93%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.625%	6.00%
Common equity tier I capital	$ 293,745	$ 283,659
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Common Equity Tier I Risk Based Capital Ratio	10.77%	10.93%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	5.125%	4.50%
Tier One Leverage Capital	$ 293,745	$ 283,659
Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Excess Tier One Leverage Capital to Average Assets	7.98%	8.33%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Subordinated Debt [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Subordinated debentures		$ 15,000

Common Equity Tier I To Total Risk Weighted Assets Capital Ratio

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Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets

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Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets

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Common equity tier I capital

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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The amount of excess Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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