Subsequent Event	6 Months Ended
Jun. 30, 2012
Subsequent Event [Abstract]
Subsequent Events [Text Block]	On July 13, 2012, Visa U.S.A. Inc. (Visa) and MasterCard each announced a preliminary settlement to resolve the plaintiffs' claims in the multi-district interchange litigation and also announced an agreement in principle to resolve the claims brought against them by certain individual retailers in that same litigation. The proposed settlement includes a cash payment to certain merchants of $6.6 billion, of which Visa is responsible for $4.4 billion, and a provision which would reduce credit card interchange income by 10 basis points over an eight month period likely to begin in mid-2013, 60 days after a court-ordered period. Other provisions include the ability for merchants to surcharge customers for credit card usage, the ability for merchant buying groups to negotiate together with Visa and MasterCard, and the ability to cancel this proposed agreement if more than 25% of all affected merchants opt out of the agreement. In accordance with the terms of a pre-funding agreement related to Visa's original initial public offering, certain member banks, including the Company have, since late 2007, participated in funding certain estimated litigation costs. On July 19, 2012, Visa announced it would add an additional $150 million to its litigation escrow account in contemplation of this litigation. The Company's portion of that funding would amount to approximately $500 thousand. The Company now estimates that the pre-tax cost of the future reduction of 10 basis points in interchange income for an eight month period, which is part of the above settlement, would amount to approximately $5.2 million. In accordance with ASC Topic 855, Subsequent Events, the preliminary settlement is considered a “Type 1” subsequent event. Both the additional funding and the interchange relief represent probable losses arising from a litigation settlement that can be reasonably estimated. Accordingly, the Company established a liability of $5.7 million as of June 30, 2012 for these anticipated costs. This additional expense, net of tax, lowered basic and diluted income per share by $.04. As a Visa member bank, the Company holds 823,447 shares of Visa Class B stock, which are convertible to Class A shares at a rate which currently approximates 43%. These shares are currently restricted from sale, other than to member banks, and carried at zero cost. On July 26, 2012, the Bank signed the formal Settlement Agreement and Release related to the class action lawsuit captioned Wolfgeher v. Commerce Bank, which was settled in December, 2011, and which alleged unfair assessment and collection of overdraft fees based upon a high-to-low posting order utilized on debit card transactions. The Bank, while admitting no wrongdoing, agreed to the settlement in order to resolve the litigation and avoid further expense. In accordance with the terms of the Settlement Agreement and Release (which remains subject to final court approval), the Bank agrees to post debit card transactions in chronological order, beginning no later than April 2013. As a result of this change in the posting order of debit card transactions, the Company currently estimates that overdraft income will be reduced on an annual basis by $6 to $8 million. The Company has various other lawsuits pending at June 30, 2012, arising in the normal course of business. While some matters pending against the Company specify damages claimed by plaintiffs, others do not seek a specified amount of damages or are at very early stages of the legal process. The Company records a loss accrual for all legal matters for which it deems a loss is probable and can be reasonably estimated. In the opinion of management, after consultation with legal counsel, none of these suits will have a significant effect on the financial condition and results of operations of the Company and the range of possible additional loss in excess of amounts accrued is not material.

On July 13, 2012, Visa U.S.A. Inc. (Visa) and MasterCard each announced a preliminary settlement to resolve the plaintiffs' claims in the multi-district interchange litigation and also announced an agreement in principle to resolve the claims brought against them by certain individual retailers in that same litigation. The proposed settlement includes a cash payment to certain merchants of $6.6 billion, of which Visa is responsible for $4.4 billion, and a provision which would reduce credit card interchange income by 10 basis points over an eight month period likely to begin in mid-2013, 60 days after a court-ordered period. Other provisions include the ability for merchants to surcharge customers for credit card usage, the ability for merchant buying groups to negotiate together with Visa and MasterCard, and the ability to cancel this proposed agreement if more than 25% of all affected merchants opt out of the agreement.

In accordance with the terms of a pre-funding agreement related to Visa's original initial public offering, certain member banks, including the Company have, since late 2007, participated in funding certain estimated litigation costs. On July 19, 2012, Visa announced it would add an additional $150 million to its litigation escrow account in contemplation of this litigation. The Company's portion of that funding would amount to approximately $500 thousand. The Company now estimates that the pre-tax cost of the future reduction of 10 basis points in interchange income for an eight month period, which is part of the above settlement, would amount to approximately $5.2 million. In accordance with ASC Topic 855, Subsequent Events, the preliminary settlement is considered a “Type 1” subsequent event. Both the additional funding and the interchange relief represent probable losses arising from a litigation settlement that can be reasonably estimated. Accordingly, the Company established a liability of $5.7 million as of June 30, 2012 for these anticipated costs. This additional expense, net of tax, lowered basic and diluted income per share by $.04.

As a Visa member bank, the Company holds 823,447 shares of Visa Class B stock, which are convertible to Class A shares at a rate which currently approximates 43%. These shares are currently restricted from sale, other than to member banks, and carried at zero cost.

On July 26, 2012, the Bank signed the formal Settlement Agreement and Release related to the class action lawsuit captioned Wolfgeher v. Commerce Bank, which was settled in December, 2011, and which alleged unfair assessment and collection of overdraft fees based upon a high-to-low posting order utilized on debit card transactions. The Bank, while admitting no wrongdoing, agreed to the settlement in order to resolve the litigation and avoid further expense. In accordance with the terms of the Settlement Agreement and Release (which remains subject to final court approval), the Bank agrees to post debit card transactions in chronological order, beginning no later than April 2013. As a result of this change in the posting order of debit card transactions, the Company currently estimates that overdraft income will be reduced on an annual basis by $6 to $8 million.

The Company has various other lawsuits pending at June 30, 2012, arising in the normal course of business. While some matters pending against the Company specify damages claimed by plaintiffs, others do not seek a specified amount of damages or are at very early stages of the legal process. The Company records a loss accrual for all legal matters for which it deems a loss is probable and can be reasonably estimated. In the opinion of management, after consultation with legal counsel, none of these suits will have a significant effect on the financial condition and results of operations of the Company and the range of possible additional loss in excess of amounts accrued is not material.