Commitments, Contingent Liabilities, and Legal Proceedings (Details) - USD ($) $ in Thousands	Jul. 22, 2024	Dec. 31, 2024
Other Commitments [Line Items]
Commitments of legally binding lease payments		$ 470,026
WV
Other Commitments [Line Items]
Commitments of legally binding lease payments		48,000
SD
Other Commitments [Line Items]
Commitments of legally binding lease payments		$ 23,000
Rotech Healthcare Holdings Inc
Other Commitments [Line Items]
Payments to acquire business in cash	$ 1,360,000
Business combination, anticipated tax benefits	40,000
Business combination, estimated consideration to be transferred	1,320,000
Business combination, termination fee	$ 70,000

The amount of anticipated tax benefits arising from the acquisition.

No definition available.

Name:	omi_BusinessCombinationAnticipatedTaxBenefitsArisingFromAcquisition
Namespace Prefix:	omi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Estimated consideration to be transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

No definition available.

+ Details

Name:	omi_BusinessCombinationEstimatedConsiderationToBeTransferred
Namespace Prefix:	omi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of termination fee to be paid upon termination of the contract.

+ References

No definition available.

+ Details

Name:	omi_BusinessCombinationTerminationFee
Namespace Prefix:	omi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147478964/842-20-50-6

+ Details

Name:	us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_OtherCommitmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479581/805-30-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-13

+ Details

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

- Details

Name:	srt_StatementGeographicalAxis=stpr_WV
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_SD
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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