XML 82 R75.htm IDEA: XBRL DOCUMENT v3.26.1

Commitments, Contingencies and Guarantees - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Jan. 31, 2025	Dec. 31, 2024
Commitments and Contingencies Disclosure [Line Items]
ACL for off-balance sheet credit exposures	$ 5,721,000	$ 8,221,000	$ 5,721,000		$ 4,138,000
Provision for off-balance sheet credit exposures	0	$ 500,000
Heartland Financial USA, Inc [Member]
Commitments and Contingencies Disclosure [Line Items]
ACL for off-balance sheet credit exposures				$ 3,600,000
Accrued Expenses and Taxes [Member]
Commitments and Contingencies Disclosure [Line Items]
ACL for off-balance sheet credit exposures	$ 5,700,000		$ 5,700,000

X

- Definition

Commitments and contingencies disclosure.

+ References

No definition available.

+ Details

Name:	umbf_CommitmentsAndContingenciesDisclosureLineItems
Namespace Prefix:	umbf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482454/460-10-45-1

+ Details

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

X

- Definition

Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

+ Details

Name:	us-gaap_OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=umbf_HeartlandFinancialUsaIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BalanceSheetLocationAxis=umbf_AccruedExpensesAndTaxesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: