Separate Financial Information of Subsidiary Guarantors of Indebtedness (Details) (USD $) In Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Condensed Consolidating Statements of Income
Net sales	$ 2,115.4	$ 2,022.9	$ 1,745.6	$ 1,700.8	$ 2,105.1	$ 2,439.0	$ 2,864.2	$ 2,434.1	$ 7,584.7	$ 9,842.4	$ 5,253.1
Cost of sales									6,505.0	7,872.4	4,549.8
Gross income	217.6	272.0	281.1	309.0	381.4	481.6	627.8	479.2	1,079.7	1,970.0	703.3
Selling, general and administrative									513.2	489.8	430.3
Amortization of purchased intangibles									60.8	60.5	62.3
Intangible asset impairment charges									4.8	25.6	1,190.2
Operating income (loss)	73.8	126.0	132.4	168.7	233.6	340.5	494.3	325.7	500.9	1,394.1	(979.5)
Interest expense									(90.7)	(187.1)	(211.4)
Interest income									4.7	3.5	3.9
Miscellaneous, net									1.6	1.0	8.8
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of unconsolidated affiliates									416.5	1,211.5	(1,178.2)
Provision for (benefit from) income taxes									143.6	414.3	(12.6)
Income (loss) from continuing operations before equity in earnings (losses) of unconsolidated affiliates									272.9	797.2	(1,165.6)
Equity in earnings (losses) of unconsolidated affiliates									0.5	(4.3)	(1.4)
Income (loss) from continuing operations, net of tax	37.5	68.4	67.9	99.6	116.6	211.2	292.6	172.5	273.4	792.9	(1,167.0)
Discontinued operations, net of tax								(2.9)		(2.9)	67.3
Net income (loss)	37.5	68.4	67.9	99.6	116.6	211.2	292.6	169.6	273.4	790.0	(1,099.7)
Net loss attributable to noncontrolling interest											0.9
Net income (loss) attributable to Oshkosh Corporation									273.4	790.0	(1,098.8)
Oshkosh Corporation
Condensed Consolidating Statements of Income
Net sales									4,540.2	7,341.9	2,796.5
Cost of sales									3,873.3	5,892.1	2,304.2
Gross income									666.9	1,449.8	492.3
Selling, general and administrative									212.0	196.9	141.5
Amortization of purchased intangibles									0.1
Operating income (loss)									454.8	1,252.9	350.8
Interest expense									(200.2)	(276.4)	(289.5)
Interest income									2.9	2.4	4.4
Miscellaneous, net									10.7	12.7	12.9
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of unconsolidated affiliates									268.2	991.6	78.6
Provision for (benefit from) income taxes									93.9	328.4	17.4
Income (loss) from continuing operations before equity in earnings (losses) of unconsolidated affiliates									174.3	663.2	61.2
Equity in earnings (losses) of consolidated subsidiaries									99.2	125.4	(1,257.3)
Equity in earnings (losses) of unconsolidated affiliates									(0.1)
Income (loss) from continuing operations, net of tax									273.4	788.6	(1,196.1)
Discontinued operations, net of tax										1.4	97.3
Net income (loss)									273.4	790.0	(1,098.8)
Net income (loss) attributable to Oshkosh Corporation									273.4	790.0	(1,098.8)
Guarantor Subsidiaries
Condensed Consolidating Statements of Income
Net sales									2,409.4	3,559.1	1,811.1
Cost of sales									2,106.5	3,119.5	1,629.3
Gross income									302.9	439.6	181.8
Selling, general and administrative									181.8	164.4	136.3
Amortization of purchased intangibles									39.8	40.2	40.8
Intangible asset impairment charges											702.1
Operating income (loss)									81.3	235.0	(697.4)
Interest expense									(82.2)	(170.6)	(153.5)
Interest income									26.4	18.6	28.2
Miscellaneous, net									(120.5)	(94.9)	(78.8)
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of unconsolidated affiliates									(95.0)	(11.9)	(901.5)
Provision for (benefit from) income taxes									(30.0)	(1.5)	(32.1)
Income (loss) from continuing operations before equity in earnings (losses) of unconsolidated affiliates									(65.0)	(10.4)	(869.4)
Equity in earnings (losses) of consolidated subsidiaries									56.0	(1.9)	(239.7)
Income (loss) from continuing operations, net of tax									(9.0)	(12.3)	(1,109.1)
Net income (loss)									(9.0)	(12.3)	(1,109.1)
Net income (loss) attributable to Oshkosh Corporation									(9.0)	(12.3)	(1,109.1)
Non-Guarantor Subsidiaries
Condensed Consolidating Statements of Income
Net sales									893.1	835.6	836.3
Cost of sales									787.4	753.0	805.3
Gross income									105.7	82.6	31.0
Selling, general and administrative									119.4	128.5	152.5
Amortization of purchased intangibles									20.9	20.3	21.5
Intangible asset impairment charges									4.8	25.6	488.1
Operating income (loss)									(39.4)	(91.8)	(631.1)
Interest expense									(3.9)	(2.5)	(5.5)
Interest income									171.0	244.9	208.4
Miscellaneous, net									111.4	83.2	74.7
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of unconsolidated affiliates									239.1	233.8	(353.5)
Provision for (benefit from) income taxes									78.3	88.1	2.8
Income (loss) from continuing operations before equity in earnings (losses) of unconsolidated affiliates									160.8	145.7	(356.3)
Equity in earnings (losses) of consolidated subsidiaries									(52.5)	0.2	0.2
Equity in earnings (losses) of unconsolidated affiliates									0.6	(4.3)	(1.4)
Income (loss) from continuing operations, net of tax									108.9	141.6	(357.5)
Discontinued operations, net of tax										(4.3)	(30.0)
Net income (loss)									108.9	137.3	(387.5)
Net loss attributable to noncontrolling interest											0.9
Net income (loss) attributable to Oshkosh Corporation									108.9	137.3	(386.6)
Eliminations
Condensed Consolidating Statements of Income
Net sales									(258.0)	(1,894.2)	(190.8)
Cost of sales									262.2	(1,892.2)	(189.0)
Gross income									4.2	(2.0)	(1.8)
Operating income (loss)									4.2	(2.0)	(1.8)
Interest expense									195.6	262.4	237.1
Interest income									(195.6)	(262.4)	(237.1)
Income (loss) from continuing operations before income taxes and equity in earnings (losses) of unconsolidated affiliates									4.2	(2.0)	(1.8)
Provision for (benefit from) income taxes									1.4	(0.7)	(0.7)
Income (loss) from continuing operations before equity in earnings (losses) of unconsolidated affiliates									2.8	(1.3)	(1.1)
Equity in earnings (losses) of consolidated subsidiaries									(102.7)	(123.7)	1,496.8
Income (loss) from continuing operations, net of tax									(99.9)	(125.0)	1,495.7
Net income (loss)									(99.9)	(125.0)	1,495.7
Net income (loss) attributable to Oshkosh Corporation									$ (99.9)	$ (125.0)	$ 1,495.7