Loans And The Allowance For Credit Losses (Allowance For Loan Losses And The Recorded Investment In Loans) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance individually evaluated for impairment	$ 178	$ 63
Ending balance collectively evaluated for impairment	12,561	12,752
Financing receivables, Ending balance individually evaluated for impairment	1,298	791
Financing receivables, Ending balance collectively evaluated for impairment	1,198,872	1,181,543
Financing receivables, Totals	1,200,170	1,182,334
Allowance for loan losses	11,989	11,833
Reserve for undisbursed lines of credit	750mbvt_ReserveForUndisbursedLinesOfCredit	982mbvt_ReserveForUndisbursedLinesOfCredit
Total allowance for credit losses	12,739	12,815	12,929	12,828
Commercial, Financial And Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance individually evaluated for impairment	68
Ending balance collectively evaluated for impairment	3,300	3,331
Financing receivables, Ending balance individually evaluated for impairment	590	134
Financing receivables, Ending balance collectively evaluated for impairment	195,192	177,463
Financing receivables, Totals	195,782	177,597
Allowance for loan losses	2,859	2,583
Reserve for undisbursed lines of credit	509	748
Total allowance for credit losses	3,368	3,331	3,378	3,354
Municipal Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance collectively evaluated for impairment	543	636
Financing receivables, Ending balance collectively evaluated for impairment	91,410	94,366
Financing receivables, Totals	91,410	94,366
Allowance for loan losses	530	623
Reserve for undisbursed lines of credit	13	13
Total allowance for credit losses	543	636	693	768
Real Estate Loans – Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance individually evaluated for impairment	110	63
Ending balance collectively evaluated for impairment	3,000	3,064
Financing receivables, Ending balance individually evaluated for impairment	708	657
Financing receivables, Ending balance collectively evaluated for impairment	460,751	468,872
Financing receivables, Totals	461,459	469,529
Allowance for loan losses	3,024	3,038
Reserve for undisbursed lines of credit	86	89
Total allowance for credit losses	3,110	3,127	3,352	3,081
Real Estate Loans – Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance collectively evaluated for impairment	5,217	5,251
Financing receivables, Ending balance collectively evaluated for impairment	419,500	412,447
Financing receivables, Totals	419,500	412,447
Allowance for loan losses	5,149	5,209
Reserve for undisbursed lines of credit	68	42
Total allowance for credit losses	5,217	5,251	5,119	5,085
Real Estate Loans – Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance collectively evaluated for impairment	438	415
Financing receivables, Ending balance collectively evaluated for impairment	28,512	23,858
Financing receivables, Totals	28,512	23,858
Allowance for loan losses	364	325
Reserve for undisbursed lines of credit	74	90
Total allowance for credit losses	438	415	360	512
Installment Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance collectively evaluated for impairment	63	13
Financing receivables, Ending balance collectively evaluated for impairment	3,454	4,504
Financing receivables, Totals	3,454	4,504
Allowance for loan losses	63	13
Total allowance for credit losses	63	13	18	18
All Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance collectively evaluated for impairment		42
Financing receivables, Ending balance collectively evaluated for impairment	53	33
Financing receivables, Totals	53	33
Allowance for loan losses		42
Total allowance for credit losses		$ 42	$ 9	$ 10

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- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(1)

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

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-Paragraph 11B

-Subparagraph (g)

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The balance of financing receivables that were collectively evaluated for impairment.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

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The balance of financing receivables that were individually evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

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