CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Net sales	$ 1,984.4	$ 2,062.3	$ 3,734.2	$ 3,930.8
Cost of sales	1,681.0	1,818.2	3,184.8	3,461.8
Gross income	303.4	244.1	549.4	469.0
Operating expenses:
Selling, general and administrative	154.3	145.4	305.6	276.5
Amortization of purchased intangibles	14.5	14.6	28.9	29.3
Total operating expenses	168.8	160.0	334.5	305.8
Operating income	134.6	84.1	214.9	163.2
Other income (expense):
Interest expense	(16.4)	(18.0)	(32.8)	(38.5)
Interest income	1.7	0.6	4.2	1.2
Miscellaneous, net	0.1	1.3	0.4	(4.3)
Income from continuing operations before income taxes and equity in earnings of unconsolidated affiliates	120.0	68.0	186.7	121.6
Provision for income taxes	34.8	24.4	55.8	36.8
Income from continuing operations before equity in earnings of unconsolidated affiliates	85.2	43.6	130.9	84.8
Equity in earnings of unconsolidated affiliates	0.7	0	1.3	0.7
Income from continuing operations, net of tax	85.9	43.6	132.2	85.5
Income (loss) from discontinued operations, net of tax	0.6	(5.6)	0.8	(8.2)
Net income	86.5	38.0	133.0	77.3
Net income attributable to noncontrolling interest	0	(0.7)	0	(1.1)
Net income attributable to Oshkosh Corporation	$ 86.5	$ 37.3	$ 133.0	$ 76.2
Earnings (loss) per share attributable to Oshkosh Corporation common shareholders-basic:
From continuing operations (in dollars per share)	$ 0.98	$ 0.47	$ 1.48	$ 0.92
From discontinued operations (in dollars per share)	$ 0.01	$ (0.06)	$ 0.01	$ (0.09)
Total earnings (loss) per share attributable to Oshkosh Corporation common shareholders-basic (in dollars per share)	$ 0.99	$ 0.41	$ 1.49	$ 0.83
Earnings (loss) per share attributable to Oshkosh Corporation common shareholders-diluted:
From continuing operations (in dollars per share)	$ 0.96	$ 0.47	$ 1.46	$ 0.92
From discontinued operations (in dollars per share)	$ 0.01	$ (0.06)	$ 0.01	$ (0.09)
Total earnings (loss) per share attributable to Oshkosh Corporation common shareholders-diluted (in dollars per share)	$ 0.97	$ 0.41	$ 1.47	$ 0.83