DESCRIPTION OF PLAN (Details) - EBP 015	12 Months Ended
Dec. 31, 2025 year
EBP, Description of Plan [Line Items]
Required service period	1 year
Participant contribution, combined, maximum percentage of eligible compensation	75.00%
Employer contribution, matching percentage	50.00%
Employer contribution, participant compensation matched, percentage	6.00%
Discretionary investment allocation allowed, maximum percentage of contributions	20.00%
Vesting percentage	100.00%
Still employed, participant age for distribution (in year)	70.5
Minimum
EBP, Description of Plan [Line Items]
Participant contribution, contribution to eligible compensation, percentage	1.00%
Participant contribution, after tax, contribution to eligible compensation, percentage	1.00%
Maximum
EBP, Description of Plan [Line Items]
Participant contribution, contribution to eligible compensation, percentage	75.00%
Participant contribution, after tax, contribution to eligible compensation, percentage	75.00%

EBP, Participant Accounts, Discretionary Investment Allocation Allowed, Maximum Percentage Of Contributions

No definition available.

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Namespace Prefix:	unp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Participant Accounts, Vesting Percentage

+ References

No definition available.

+ Details

Name:	unp_EBPParticipantAccountsVestingPercentage
Namespace Prefix:	unp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Participant Contribution, Combined, Maximum Annual Compensation to Total Compensation, Percentage

+ References

No definition available.

+ Details

Name:	unp_EBPParticipantContributionCombinedMaximumAnnualCompensationToTotalCompensationPercentage
Namespace Prefix:	unp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Participant Contribution, Contribution to Eligible Compensation, After Tax, Percentage

+ References

No definition available.

+ Details

Name:	unp_EBPParticipantContributionContributionToEligibleCompensationAfterTaxPercentage
Namespace Prefix:	unp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Participant Contribution, Contribution to Eligible Compensation, Percentage

+ References

No definition available.

+ Details

Name:	unp_EBPParticipantContributionContributionToEligibleCompensationPercentage
Namespace Prefix:	unp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Requisite Service Period

+ References

No definition available.

+ Details

Name:	unp_EBPRequisiteServicePeriod
Namespace Prefix:	unp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

EBP, Still Employed, Participant Age For Distribution

+ References

No definition available.

+ Details

Name:	unp_EBPStillEmployedParticipantAgeForDistribution
Namespace Prefix:	unp_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanDescriptionOfPlanLineItems
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of employer matching contribution on eligible participant contribution to employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478873/962-325-55-17

+ Details

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Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of participant compensation eligible for employer matching contribution for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
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Balance Type:
Period Type: