Medical Costs Payable, Incurred and Paid Medical Cost Development (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Acquisitions (dispositions), net	$ (755)
Medical costs payable included within businesses held for sale	(179)	$ 0	$ 0
Health Insurance Product Line [Member]
Net Incurred Medical Costs	507,041
Net Cumulative Medical Payments	(472,002)
Net remaining outstanding liabilities prior to 2023	119
Total Medical costs payable	34,224
Health Insurance Product Line [Member] \| Short-duration Insurance Contracts, Accident Year 2023 [Member]
Net Incurred Medical Costs	242,156	242,734
Net Cumulative Medical Payments	(240,112)	$ (211,380)
Health Insurance Product Line [Member] \| Short-duration Insurance Contracts, Accident Year 2024 [Member]
Net Incurred Medical Costs	264,885
Net Cumulative Medical Payments	$ (231,890)

Acquisitions (dispositions), net

No definition available.

Name:	unh_AcquisitionsDispositionsNet
Namespace Prefix:	unh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Medical costs payable included within businesses held for sale

+ References

No definition available.

+ Details

Name:	unh_MedicalCostsPayableIncludedWithinBusinessesHeldForSale
Namespace Prefix:	unh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after reinsurance, of paid claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

+ Details

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

- Definition

Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

+ Details

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

- Definition

Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 9E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-9E

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 4C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-4C

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-4B

+ Details

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

- Definition

Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts for accident years not separately presented in claim development information. Excludes unallocated claim adjustment expense.

+ References

+ Details

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

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_HealthInsuranceProductLineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortdurationInsuranceContractsAccidentYear2015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortdurationInsuranceContractsAccidentYear2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: