XML 158 R142.htm IDEA: XBRL DOCUMENT v3.20.4

Fair Value Measurements (Schedule of Fair Value Disclosures Measured On Nonrecurring Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent loans, fair value	$ 12,961	$ 422
Collateral dependent loans, Total Gains (Losses)	(7,763)	(263)
Mortgage servicing rights, fair value	6,249	7,749
Mortgage servicing rights, Total Gains (Losses)	(1,776)	(327)
Long Lived Assets Nonrecurring Basis, fair value	811	1,098
Long Lived Assets Nonrecurring Basis Gains (Losses)	(9)	(362)
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent loans, fair value	0	0
Mortgage servicing rights, fair value	0	0
Long Lived Assets Nonrecurring Basis, fair value	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent loans, fair value	0	0
Mortgage servicing rights, fair value	0	0
Long Lived Assets Nonrecurring Basis, fair value	0	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Collateral dependent loans, fair value	12,961	422
Mortgage servicing rights, fair value	6,249	7,749
Long Lived Assets Nonrecurring Basis, fair value	$ 811	$ 1,098

X

- Definition

Represents the fair value of loans measured on a nonrecurring basis during the period(s) presented and which are still held as of the period end.

+ References

No definition available.

+ Details

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

X

- Definition

Represents the gains and losses on loans measured on a nonrecurring basis during the period(s) presented.

+ References

No definition available.

+ Details

Name:	cbsh_LoansNonrecurringBasisGainsLosses
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Represents the fair value of long-lived assets measured on a nonrecurring basis during the period(s) presented and which are still held as of the period end.

+ References

No definition available.

+ Details

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

X

- Definition

Represents the gains and losses on long-lived assets measured on a nonrecurring basis during the period(s) presented.

+ References

No definition available.

+ Details

Name:	cbsh_LongLivedAssetsNonrecurringBasisGainsLosses
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Represents the mortgage servicing rights measured on a nonrecurring basis during the period(s) presented and which are still held as of the period end.

+ References

No definition available.

+ Details

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

X

- Definition

Represents the gains and losses on mortgage servicing rights measured on a nonrecurring basis during the period(s) presented.

+ References

No definition available.

+ Details

Name:	cbsh_MortgageServicingRightsNonrecurringBasisGainsLosses
Namespace Prefix:	cbsh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: