Debt Instrument, Call Date, Earliest Period

No definition available.

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Namespace Prefix:	bhb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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-SubTopic 210
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Topic 470
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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+ Details

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Period Type:	instant

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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BORROWED FUNDS - Narrative (Details) - USD ($)		1 Months Ended
BORROWED FUNDS - Narrative (Details) - USD ($)	Mar. 30, 2014	Apr. 30, 2008	Dec. 31, 2018	Dec. 31, 2017	Oct. 29, 2014
Debt Instrument [Line Items]
Short-term debt			$ 647,894,000	$ 649,498,000
Amount			75,902,000	180,223,000
Financial Guarantee \| NHTB Capital Trust III
Debt Instrument [Line Items]
Debentures issued by variable interest entities	$ 20,600,000
Subordinated debt
Debt Instrument [Line Items]
Principal amount of debt issued					$ 17,000,000.0
Fixed interest rate					6.75%
LIBOR \| Financial Guarantee
Debt Instrument [Line Items]
Interest rate margin	2.79%
Advances from the FHLB
Debt Instrument [Line Items]
Maximum borrowing capacity on line of credit			1,000,000
Current balance on line of credit			0	0
Short-term debt			611,683,000	608,792,000
Amount			32,929,000	137,190,000
Federal Reserve Bank Advances
Debt Instrument [Line Items]
Maximum borrowing capacity on line of credit			118,599,000
Short-term debt			0	0
Federal Home Loan Bank Certificates and Obligations FHLB Callable Advances
Debt Instrument [Line Items]
Amount			0	27,000,000
Federal Home Loan Bank Certificates and Obligations FHLB Amortizing Advances
Debt Instrument [Line Items]
Amount			330,000	683,000
Subordinated borrowings
Debt Instrument [Line Items]
Amount			$ 37,973,000	$ 38,033,000
Maturity period (in years)		15 years
Principal amount of debt issued		$ 5,000,000.0
Earliest callable period without penalties		5 years
Effective interest rate			6.23819%	5.04%
Subordinated borrowings \| LIBOR
Debt Instrument [Line Items]
Interest rate margin		3.45%