Separate Financial Information of Subsidiary Guarantors of Indebtedness Details 3 (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Condensed financial statements, captions
Net cash provided (used) by operating activities	$ 83.8	$ 73.2
Additions to property, plant and equipment	(14.2)	(21.3)
Additions to equipment held for rental	(12.9)	(15.0)
Proceeds from sale of equipment held for rental	5.3	18.7
Intercompany investing	0.0	0.0
Other investing activities	(0.2)	(0.6)
Net cash provided (used) by investing activities	(22.0)	(18.2)
Proceeds from issuance of debt (original maturities greater than three months)	0.0	153.6
Repayments of debt (original maturities greater than three months)	(20.0)	(135.0)
Net increase in short-term debt	0.0	28.2
Repurchases of Common Stock	(3.0)	(101.5)
Dividends paid	(15.6)	(14.1)
Proceeds from exercise of stock options	26.2	1.4
Excess tax benefit from stock-based compensation	0.0	0.8
Intercompany financing	0.0	0.0
Net cash used by financing activities	(12.4)	(66.6)
Effect of exchange rate changes on cash	(1.7)	2.4
Increase (decrease) in cash and cash equivalents	47.7	(9.2)
Cash and cash equivalents at beginning of period	321.9	42.9
Cash and cash equivalents at end of period	369.6	33.7
Oshkosh Corporation
Condensed financial statements, captions
Net cash provided (used) by operating activities	(42.8)	(83.3)
Additions to property, plant and equipment	(0.4)	(7.0)
Additions to equipment held for rental	0.0	0.0
Proceeds from sale of equipment held for rental	0.0	0.0
Intercompany investing	0.0	0.0
Other investing activities	(0.2)	(0.5)
Net cash provided (used) by investing activities	(0.6)	(7.5)
Proceeds from issuance of debt (original maturities greater than three months)		150.0
Repayments of debt (original maturities greater than three months)	(20.0)	(135.0)
Net increase in short-term debt		28.2
Repurchases of Common Stock	(3.0)	(101.5)
Dividends paid	(15.6)	(14.1)
Proceeds from exercise of stock options	26.2	1.4
Excess tax benefit from stock-based compensation		0.8
Intercompany financing	93.9	158.4
Net cash used by financing activities	81.5	88.2
Effect of exchange rate changes on cash	0.0	0.0
Increase (decrease) in cash and cash equivalents	38.1	(2.6)
Cash and cash equivalents at beginning of period	285.4	14.8
Cash and cash equivalents at end of period	323.5	12.2
Guarantor Subsidiaries
Condensed financial statements, captions
Net cash provided (used) by operating activities	67.0	86.8
Additions to property, plant and equipment	(9.1)	(5.1)
Additions to equipment held for rental	0.0	0.0
Proceeds from sale of equipment held for rental	0.0	0.6
Intercompany investing	498.1	(76.6)
Other investing activities	0.0	(0.1)
Net cash provided (used) by investing activities	489.0	(81.2)
Proceeds from issuance of debt (original maturities greater than three months)		0.0
Repayments of debt (original maturities greater than three months)	0.0	0.0
Net increase in short-term debt		0.0
Repurchases of Common Stock	0.0	0.0
Dividends paid	0.0	0.0
Proceeds from exercise of stock options	0.0	0.0
Excess tax benefit from stock-based compensation		0.0
Intercompany financing	(553.0)	(6.5)
Net cash used by financing activities	(553.0)	(6.5)
Effect of exchange rate changes on cash	(0.2)	0.2
Increase (decrease) in cash and cash equivalents	2.8	(0.7)
Cash and cash equivalents at beginning of period	1.7	6.3
Cash and cash equivalents at end of period	4.5	5.6
Non-Guarantor Subsidiaries
Condensed financial statements, captions
Net cash provided (used) by operating activities	59.6	69.7
Additions to property, plant and equipment	(4.7)	(9.2)
Additions to equipment held for rental	(12.9)	(15.0)
Proceeds from sale of equipment held for rental	5.3	18.1
Intercompany investing	(39.0)	(75.3)
Other investing activities	0.0	0.0
Net cash provided (used) by investing activities	(51.3)	(81.4)
Proceeds from issuance of debt (original maturities greater than three months)		3.6
Repayments of debt (original maturities greater than three months)	0.0	0.0
Net increase in short-term debt		0.0
Repurchases of Common Stock	0.0	0.0
Dividends paid	0.0	0.0
Proceeds from exercise of stock options	0.0	0.0
Excess tax benefit from stock-based compensation		0.0
Intercompany financing	0.0	0.0
Net cash used by financing activities	0.0	3.6
Effect of exchange rate changes on cash	(1.5)	2.2
Increase (decrease) in cash and cash equivalents	6.8	(5.9)
Cash and cash equivalents at beginning of period	34.8	21.8
Cash and cash equivalents at end of period	41.6	15.9
Eliminations
Condensed financial statements, captions
Net cash provided (used) by operating activities	0.0	0.0
Additions to property, plant and equipment	0.0	0.0
Additions to equipment held for rental	0.0	0.0
Proceeds from sale of equipment held for rental	0.0	0.0
Intercompany investing	(459.1)	151.9
Other investing activities	0.0	0.0
Net cash provided (used) by investing activities	(459.1)	151.9
Proceeds from issuance of debt (original maturities greater than three months)		0.0
Repayments of debt (original maturities greater than three months)	0.0	0.0
Net increase in short-term debt		0.0
Repurchases of Common Stock	0.0	0.0
Dividends paid	0.0	0.0
Proceeds from exercise of stock options	0.0	0.0
Excess tax benefit from stock-based compensation		0.0
Intercompany financing	459.1	(151.9)
Net cash used by financing activities	459.1	(151.9)
Effect of exchange rate changes on cash	0.0	0.0
Increase (decrease) in cash and cash equivalents	0.0	0.0
Cash and cash equivalents at beginning of period	0.0	0.0
Cash and cash equivalents at end of period	$ 0.0	$ 0.0