Guarantees - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Indirect Guarantee of Deferred Payment and Lease Payment Agreements
Guarantee Obligations [Line Items]
Aggregate indebtedness to customers under credit guarantees	$ 594.7
Estimated maximum loss exposure under contracts	109.4
Indirect Guarantee of Deferred Payment and Lease Payment Agreements \| Non-Contingent Portion
Guarantee Obligations [Line Items]
Guarantee obligations loss provision	11.9	$ 12.0
Indirect Guarantee of Deferred Payment and Lease Payment Agreements \| Contingent Portion
Guarantee Obligations [Line Items]
Guarantee obligations loss provision	4.5	$ 5.0
Residual Value Guarantee
Guarantee Obligations [Line Items]
Estimated maximum loss exposure under contracts	9.4
Customer equipment value including a residual value guarantee	$ 80.7

Customer equipment value including a residual value guarantee.

No definition available.

Name:	osk_EquipmentValueSoldIncludingResidualValueGuarantee
Namespace Prefix:	osk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate amount of indebtedness of others which the Company is a party to through guarantee agreements.

+ References

No definition available.

+ Details

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Namespace Prefix:	osk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the reserve to cover probable loss on account of customer guarantee obligations as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	osk_
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

+ Details

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

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482425/460-10-50-4

+ Details

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

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=osk_IndirectGuaranteeOfDeferredPaymentAndLeasePaymentAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ContingentConsiderationByTypeAxis=osk_NonContingentPortionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ContingentConsiderationByTypeAxis=osk_ContingentPortionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=osk_ResidualValueGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: