Securities - Schedule of Components of Investment Securities Losses, Net (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Available-for-sale debt securities:
Gains realized on sales	$ 0	$ 2,720
Equity securities with readily determinable fair values:
Fair value adjustments, net	(1,722)	(13,918)
Equity securities without readily determinable fair values:
Fair value adjustments, net	1,200	2,862
Total investment securities losses, net	$ (522)	$ (8,336)

Equity securities with out readily determinable fair values adjustments net.

No definition available.

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

- Definition

Equity securities with readily determinable fair values abstract.

+ References

No definition available.

+ Details

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

- Definition

Equity securities with readily determinable fair values adjustments net.

+ References

No definition available.

+ Details

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

- Definition

Amount of unrealized and realized gain (loss) on investment in debt and equity securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(9)(a))
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(7)(c))
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27357-111563

+ Details

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

- References

No definition available.

+ Details

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