Loans And The Allowance For Credit Losses (Nonperforming Loans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Loans And The Allowance For Credit Losses [Abstract]
Nonaccrual loans	$ 598	$ 425
Loans past due greater than 90 days and accruing	0	75
Troubled debt restructurings ("TDRs")	193	406
Total nonperforming loans	$ 791	$ 906

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

No definition available.

+ Details

Name:	mbvt_ImpairedFinancingReceivableRecordedInvestments
Namespace Prefix:	mbvt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Nonaccrual non-troubled debt restructured loans.

+ References

No definition available.

+ Details

Name:	mbvt_NonaccrualNonTroubledDebtRestructuredLoans
Namespace Prefix:	mbvt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

+ Details

Name:	us-gaap_FinancingReceivableModificationsRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5111-111524

+ Details

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