Regulatory Capital Requirements (Schedule Of Capital Amounts And Ratios On Consolidated Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
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	$ 3,881,024	$ 3,600,920
Total Capital (to risk-weighted assets), Actual Ratio	16.03%	14.89%
Total Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,937,322	$ 1,934,274
Total Capital (to risk-weighted assets), Minimum Capital Requirement Ratio	8.00%	8.00%
Tier I Capital (to risk-weighted assets), Actual Amount	$ 3,693,089	$ 3,417,223
Tier I Capital (to risk-weighted assets), Actual Ratio	15.25%	14.13%
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,452,992	$ 1,450,705
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	$ 3,693,089	$ 3,417,223
Tier I Common Capital (to rIsk-weighted assets), Actual Rato	15.25%	14.13%
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,089,744	$ 1,088,029
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	$ 3,693,089	$ 3,417,223
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Ratio	11.25%	10.34%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Amount	$ 1,313,377	$ 1,322,102
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	$ 3,313,640	$ 3,125,987
Total Capital (to risk-weighted assets), Actual Ratio	13.81%	13.05%
Total Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,919,257	$ 1,916,529
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	$ 2,399,071	$ 2,395,661
Total Capital (to risk-weighted assets), Well-Capitalized Capital Requirement Ratio	10.00%	10.00%
Tier I Capital (to risk-weighted assets), Actual Amount	$ 3,125,706	$ 2,942,291
Tier I Capital (to risk-weighted assets), Actual Ratio	13.03%	12.28%
Tier I Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,439,443	$ 1,437,397
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	$ 1,919,257	$ 1,916,529
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	$ 3,125,706	$ 2,942,291
Tier I Common Capital (to rIsk-weighted assets), Actual Rato	13.03%	12.28%
Tier I Common Capital (to risk-weighted assets), Minimum Capital Requirement Amount	$ 1,079,582	$ 1,078,047
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	$ 1,559,396	$ 1,557,180
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	$ 3,125,706	$ 2,942,291
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Actual Ratio	9.56%	8.86%
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Minimum Capital Requirement Amount	$ 1,307,174	$ 1,328,220
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	$ 1,633,968	$ 1,660,275
Tier I Capital (to adjusted quarterly average assets) (Leverage Ratio), Well-Capitalized Capital Requirement Ratio	5.00%	5.00%

Tier One Risk Based Common Capital

No definition available.

Name:	cbsh_TierOneRiskBasedCommonCapital
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Tier One Risk Based Common Capital Required for Common Capital Adequacy

+ References

No definition available.

+ Details

Name:	cbsh_TierOneRiskBasedCommonCapitalRequiredforCommonCapitalAdequacy
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Tier One Risk Based Common Capital Required for Common Capital Adequacy to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	cbsh_TierOneRiskBasedCommonCapitalRequiredforCommonCapitalAdequacytoRiskWeightedAssets
Namespace Prefix:	cbsh_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier One Risk Based Common Capital Required to be Well Capitalized

+ References

No definition available.

+ Details

Name:	cbsh_TierOneRiskBasedCommonCapitalRequiredtobeWellCapitalized
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Tier One Risk Based Common Capital Required to be Well Capitalized to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	cbsh_TierOneRiskBasedCommonCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets
Namespace Prefix:	cbsh_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier One Risk Based Common Capital to RIsk Weighted Assets

+ References

No definition available.

+ Details

Name:	cbsh_TierOneRiskBasedCommonCapitaltoRIskWeightedAssets
Namespace Prefix:	cbsh_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of total capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_Capital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of minimum total risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum total risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Tier 1 leverage capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of minimum Tier 1 leverage capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 leverage capital to average assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 leverage capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 leverage capital to average assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 capital to average assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Tier 1 risk-based capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of minimum Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_ConsolidatedEntitiesAxis=us-gaap_ConsolidatedEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=cbsh_CommerceBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: