Separate Financial Information of Subsidiary Guarantors of Indebtedness (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Condensed financial statements, captions
Net income	$ 46.5	$ 39.3
Change in fair value of derivative instruments	0	1.4
Employee pension and postretirement benefits	1.0	1.5
Currency translation adjustments	8.6	(8.1)
Total other comprehensive income (loss), net of tax	9.6	(5.2)
Comprehensive income	56.1	34.1
Comprehensive (income) loss attributable to the noncontrolling interest	0	(0.4)
Comprehensive income attributable to Oshkosh Corp.	56.1	33.7
Non-Guarantor Subsidiaries
Condensed financial statements, captions
Net income	61.7	32.0
Change in fair value of derivative instruments	0	0
Employee pension and postretirement benefits	0	0
Currency translation adjustments	8.6	(10.3)
Total other comprehensive income (loss), net of tax	8.6	(10.3)
Comprehensive income	70.3	21.7
Comprehensive (income) loss attributable to the noncontrolling interest	0	(0.4)
Comprehensive income attributable to Oshkosh Corp.	70.3	21.3
Eliminations
Condensed financial statements, captions
Net income	(91.8)	(37.2)
Change in fair value of derivative instruments	0	0
Employee pension and postretirement benefits	0	0
Currency translation adjustments	(8.6)	8.1
Total other comprehensive income (loss), net of tax	(8.6)	8.1
Comprehensive income	(100.4)	(29.1)
Comprehensive (income) loss attributable to the noncontrolling interest	0	0
Comprehensive income attributable to Oshkosh Corp.	(100.4)	(29.1)
Oshkosh Corporation
Condensed financial statements, captions
Net income	46.5	38.9
Change in fair value of derivative instruments	0	1.4
Employee pension and postretirement benefits	1.0	1.5
Currency translation adjustments	8.6	(8.1)
Total other comprehensive income (loss), net of tax	9.6	(5.2)
Comprehensive income	56.1	33.7
Comprehensive (income) loss attributable to the noncontrolling interest	0	0
Comprehensive income attributable to Oshkosh Corp.	56.1	33.7
Guarantor Subsidiaries
Condensed financial statements, captions
Net income	30.1	5.6
Change in fair value of derivative instruments	0	0
Employee pension and postretirement benefits	0	0
Currency translation adjustments	0	2.2
Total other comprehensive income (loss), net of tax	0	2.2
Comprehensive income	30.1	7.8
Comprehensive (income) loss attributable to the noncontrolling interest	0	0
Comprehensive income attributable to Oshkosh Corp.	$ 30.1	$ 7.8