Legal Proceedings	9 Months Ended
Sep. 30, 2012
Legal Proceedings [Abstract]
Legal Matters and Contingencies [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. The Company 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. Accordingly, the Company has established a liability for these anticipated costs. 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 million to $8 million.

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.

The Company 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. Accordingly, the Company has established a liability for these anticipated costs.

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 million to $8 million.