Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Assets
Securities held-to-maturity, fair value	$ 43,182,000	$ 42,234,000	$ 39,297,000
Shareholder's Equity
Preferred stock, shares authorized (in shares)	1,000,000us-gaap_PreferredStockSharesAuthorized	1,000,000us-gaap_PreferredStockSharesAuthorized	1,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued (in shares)	25us-gaap_PreferredStockSharesIssued	25us-gaap_PreferredStockSharesIssued	25us-gaap_PreferredStockSharesIssued
Preferred stock, shares outstanding (in shares)	25us-gaap_PreferredStockSharesOutstanding	25us-gaap_PreferredStockSharesOutstanding	25us-gaap_PreferredStockSharesOutstanding
Preferred stock liquidation value	$ 100,000CMTV_PreferredStockLiquidationValue	$ 100,000CMTV_PreferredStockLiquidationValue	$ 100,000CMTV_PreferredStockLiquidationValue
Common stock par value (in dollars per share)	$ 2.50	$ 2.50	$ 2.50
Common stock, shares authorized (in shares)	15,000,000us-gaap_CommonStockSharesAuthorized	15,000,000us-gaap_CommonStockSharesAuthorized	10,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (in shares)	5,159,512us-gaap_CommonStockSharesIssued	5,142,475us-gaap_CommonStockSharesIssued	5,091,506us-gaap_CommonStockSharesIssued
Treasury stock (in shares)	210,101us-gaap_TreasuryStockShares	210,101us-gaap_TreasuryStockShares	210,101us-gaap_TreasuryStockShares

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