XML 84 R68.htm IDEA: XBRL DOCUMENT v3.20.4

Loans And Allowance For Credit Losses (Collateral-Dependent Loans) (Details) - Commercial Portfolio Segment [Member] $ in Thousands	Dec. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Amortized Cost	$ 16,790
Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business, Amortized Cost	15,804
Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business Real Estate, Amortized Cost	986
Business Assets [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Amortized Cost	13,109
Business Assets [Member] | Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business, Amortized Cost	13,109
Business Assets [Member] | Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business Real Estate, Amortized Cost	0
Future Revenue Streams [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Amortized Cost	986
Future Revenue Streams [Member] | Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business, Amortized Cost	0
Future Revenue Streams [Member] | Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business Real Estate, Amortized Cost	986
Energy Service [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Amortized Cost	2,695
Energy Service [Member] | Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business, Amortized Cost	2,695
Energy Service [Member] | Real Estate - Business [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Collateral Dependent Loans, Business Real Estate, Amortized Cost	$ 0

X

- Definition

Collateral Dependent Loans, Amortized Cost

+ References

No definition available.

+ Details

Name:	cbsh_CollateralDependentLoansAmortizedCost
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Collateral Dependent Loans, Business, Amortized Cost

+ References

No definition available.

+ Details

Name:	cbsh_CollateralDependentLoansBusinessAmortizedCost
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Collateral Dependent Loans, Business Real Estate, Amortized Cost

+ References

No definition available.

+ Details

Name:	cbsh_CollateralDependentLoansBusinessRealEstateAmortizedCost
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbsh_BusinessLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbsh_BusinessRealEstateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=cbsh_BusinessAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=cbsh_FutureRevenueStreamsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=us-gaap_EnergyServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: