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Regulatory Capital Requirements (Schedule Of Capital Amounts And Ratios On Consolidated Basis) (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
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Total Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio | 10.00% |
Tier I Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio | 8.00% |
Tier I Common Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio | 6.50% |
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Well-Capitalized Capital Requirement Ratio | 5.00% |
Commerce Bancshares, Inc. (Consolidated) [Member] |  |
Total Capital (to risk-weighted assets), Actual Amount | $ 3,189,432 | $ 3,052,079
Total Capital (to risk-weighted assets), Actual Ratio | 14.82% | 15.48%
Total Capital (to risk-weighted assets), Minimum Capital Requirement Amount | $ 1,721,317 | $ 1,577,105
Total Capital (to risk-weighted assets), Minimum Capital Requirement Ratio | 8.00% | 8.00%
Tier I Capital (to risk-weighted assets), Actual Amount | $ 2,950,926 | $ 2,890,322
Tier I Capital (to risk-weighted assets), Actual Ratio | 13.71% | 14.66%
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Amount | $ 1,290,988 | $ 1,182,829
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Ratio | 6.00% | 6.00%
Tier I Common Capital (to risk-weighted assets), Actual Amount | $ 2,950,926 | $ 2,745,538
Tier I Common Capital (to rIsk-weighted assets), Actual Rato | 13.71% | 13.93%
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Amount | $ 968,241 | $ 887,122
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Ratio | 4.50% | 4.50%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Amount | $ 2,950,926 | $ 2,890,322
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Ratio | 9.45% | 11.38%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Amount | $ 1,249,584 | $ 1,015,771
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Ratio | 4.00% | 4.00%
Commerce Bank [Member] |  |
Total Capital (to risk-weighted assets), Actual Amount | $ 2,844,675 | $ 2,583,676
Total Capital (to risk-weighted assets), Actual Ratio | 13.30% | 13.19%
Total Capital (to risk-weighted assets), Minimum Capital Requirement Amount | $ 1,710,778 | $ 1,566,866
Total Capital (to risk-weighted assets), Minimum Capital Requirement Ratio | 8.00% | 8.00%
Total Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Amount | $ 2,138,472 | $ 1,958,583
Total Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio | 10.00% | 10.00%
Tier I Capital (to risk-weighted assets), Actual Amount | $ 2,606,169 | $ 2,421,919
Tier I Capital (to risk-weighted assets), Actual Ratio | 12.19% | 12.37%
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Amount | $ 1,283,083 | $ 1,175,150
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Ratio | 6.00% | 6.00%
Tier I Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Amount | $ 1,710,778 | $ 1,566,866
Tier I Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio | 8.00% | 8.00%
Tier I Common Capital (to risk-weighted assets), Actual Amount | $ 2,606,169 | $ 2,421,919
Tier I Common Capital (to rIsk-weighted assets), Actual Rato | 12.19% | 12.37%
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Amount | $ 962,312 | $ 881,362
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Ratio | 4.50% | 4.50%
Tier I Common Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Amount | $ 1,390,007 | $ 1,273,079
Tier I Common Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio | 6.50% | 6.50%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Amount | $ 2,606,169 | $ 2,421,919
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Ratio | 8.36% | 9.57%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Amount | $ 1,246,470 | $ 1,012,232
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Ratio | 4.00% | 4.00%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Well-Capitalized Capital Requirement Amount | $ 1,558,087 | $ 1,265,290
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Well-Capitalized Capital Requirement Ratio | 5.00% | 5.00%

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