CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Net sales	$ 1,761.0	$ 1,875.7
Cost of sales	1,514.7	1,654.2
Gross income	246.3	221.5
Operating expenses:
Selling, general and administrative	151.1	131.4
Amortization of purchased intangibles	14.4	14.7
Total operating expenses	165.5	146.1
Operating income	80.8	75.4
Other income (expense):
Interest expense	(16.7)	(20.6)
Interest income	2.5	0.6
Miscellaneous, net	0.3	(5.6)
Income from continuing operations before income taxes and equity in earnings of unconsolidated affiliates	66.9	49.8
Provision for income taxes	21.0	11.1
Income from continuing operations before equity in earnings of unconsolidated affiliates	45.9	38.7
Equity in earnings of unconsolidated affiliates	0.6	0.7
Income from continuing operations, net of tax	46.5	39.4
Income (loss) from discontinued operations, net of tax	0	(0.1)
Net income	46.5	39.3
Net income attributable to noncontrolling interest	0	(0.4)
Net income attributable to Oshkosh Corporation	$ 46.5	$ 38.9
Earnings (loss) per share attributable to Oshkosh Corporation common shareholders-basic:
From continuing operations (in dollars per share)	$ 0.51	$ 0.43
From discontinued operations (in dollars per share)	$ 0.00	$ (0.01)
Total earnings (loss) per share attributable to Oshkosh Corporation common shareholders-basic (in dollars per share)	$ 0.51	$ 0.42
Earnings (loss) per share attributable to Oshkosh Corporation common shareholders-diluted:
From continuing operations (in dollars per share)	$ 0.51	$ 0.43
From discontinued operations (in dollars per share)	$ 0.00	$ (0.01)
Total earnings (loss) per share attributable to Oshkosh Corporation common shareholders-diluted (in dollars per share)	$ 0.51	$ 0.42