Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Dec. 31, 2013
Commitments And Contingencies [Abstract]
Contingent Obligations Under Standby Letters Of Credit	$ 4.57	$ 4.73
Expiration term of contingent obligations, months	12 months

Contingent Obligations Under Standby Letters Of Credit

No definition available.

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