Hedging adjustments amortized through contractual maturity date in connection with terminated hedge.

No definition available.

Name:	umbf_HedgingAdjustmentsAmortizedThroughContractualMaturityDateInConnectionWithTerminatedHedge
Namespace Prefix:	umbf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest rate floor termination date.

+ References

No definition available.

+ Details

Name:	umbf_InterestRateFloorTerminationDate
Namespace Prefix:	umbf_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Unrealized gain (loss) on interest rate cash flow hedges net of tax accumulated other comprehensive income (loss).

+ References

No definition available.

+ Details

Name:	umbf_UnrealizedGainLossOnInterestRateCashFlowHedgesNetOfTaxAccumulatedOtherComprehensiveIncomeLoss
Namespace Prefix:	umbf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Unrealized gain reclassification to earnings, remaining term.

+ References

No definition available.

+ Details

Name:	umbf_UnrealizedGainReclassificationToEarningsRemainingTerm
Namespace Prefix:	umbf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4H

+ Details

Name:	us-gaap_CollateralAlreadyPostedAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4H

+ Details

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

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value of asset after deduction of liability.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueNetAssetLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480870/815-30-50-1

+ Details

Name:	us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-SubTopic 30
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480870/815-30-50-1

+ Details

Name:	us-gaap_MaximumLengthOfTimeHedgedInInterestRateCashFlowHedge1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_NumberOfInterestRateDerivativesHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of unrealized gain (loss) related to the increase or decrease in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4C

+ Details

Name:	us-gaap_UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_FairValueHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_InterestExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateFloorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_InterestIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivatives and Hedging Activities - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) Derivative	Dec. 31, 2022 USD ($) Derivative	Aug. 28, 2020 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedging adjustments amortized through contractual maturity date in connection with terminated hedge	$ 11,500,000
Termination value of derivatives in net liability position	0
Collateral posted for derivative instruments	$ 0
Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Interest rate hedging exposure to variability in future cash flows for forecasted transactions, maximum period	13 years
Interest Rate Swap [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Fair Value Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount		$ 254,600,000
Number of interest rate swaps \| Derivative		3
Interest Rate Swap [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	$ 51,500,000	$ 51,500,000
Number of interest rate swaps \| Derivative	2	2
Interest Rate Swap [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedging [Member] \| Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification from AOCI to interest	$ 1,400,000
Interest Rate Swap [Member] \| Derivatives not Designated as Hedging Instruments [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	$ 4,000,000,000	$ 3,500,000,000
Number of interest rate swaps \| Derivative	250	230
Interest Rate Floor [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount			$ 750,000,000
Net asset fair value			$ 34,100,000
Unrealized gain on terminated interest rate floor remaining in AOCI, pre tax	$ 3,700,000	$ 7,400,000
Unrealized gain on terminated interest rate floor remaining in AOCI, net of tax	$ 2,800,000	$ 5,600,000
Unrealized gain reclassification to earnings, remaining term	10 months 24 days
Interest rate floor termination date	Aug. 28, 2020
Interest Rate Floor [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedging [Member] \| Increase To Interest Income [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification from AOCI to interest	$ 3,700,000