Fair Values of Financial Instruments - Plan's investment assets at fair value (Details) - Bar Harbor Bankshares 401(k) Plan - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Fair Values of Financial Instruments
Investments, at fair value	$ 72,936,966	$ 62,114,885
Common Collective Trust
Fair Values of Financial Instruments
Investments, at fair value	1,697,248	2,027,315
Fair Value, Level 1, Level 2, and Level 3
Fair Values of Financial Instruments
Investments, at fair value	71,239,718	60,087,570
Fair Value, Level 1, Level 2, and Level 3 \| Mutual funds
Fair Values of Financial Instruments
Investments, at fair value	66,904,927	55,630,182
Fair Value, Level 1, Level 2, and Level 3 \| Common Stock of BHB
Fair Values of Financial Instruments
Investments, at fair value	4,335,091	4,457,388
Level 1
Fair Values of Financial Instruments
Investments, at fair value	71,239,718	60,087,570
Level 1 \| Mutual funds
Fair Values of Financial Instruments
Investments, at fair value	66,904,627	55,630,182
Level 1 \| Common Stock of BHB
Fair Values of Financial Instruments
Investments, at fair value	4,335,091	4,457,388
Net Asset Value \| Common Collective Trust
Fair Values of Financial Instruments
Investments, at fair value	$ 1,697,248	$ 2,027,315

Fair value of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract not meeting fully-benefit responsive investment criteria.

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+ Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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