Document and Entity Information (USD $)	12 Months Ended
	Sep. 30, 2012	Nov. 09, 2012	Mar. 31, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	OSHKOSH CORP
Entity Central Index Key	0000775158
Document Type	10-K
Document Period End Date	Sep. 30, 2012
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,123,214,322
Entity Common Stock, Shares Outstanding (in shares)		91,565,824
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY