Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax	$ (775.6)	$ (1,197.1)	$ (775.6)	$ (1,197.1)	$ (817.7)	$ (1,225.3)
Other comprehensive income (loss) before reclassifications, net of tax			13.3	(15.1)
Amounts reclassified from accumulated other comprehensive loss, net of tax			28.8	43.3
Other comprehensive income (loss), net of tax	17.6	(17.0)	42.1	28.2
Sales	1,429.1	1,363.5	2,851.4	2,697.7
Cost of Sales	(825.1)	(794.2)	(1,635.5)	(1,569.0)
Total before tax	248.4	227.1	521.2	444.3
Tax (expense) benefit	(68.1)	(51.2)	(142.8)	(107.0)
Net of tax	180.3	175.9	378.4	337.3
Pension and other postretirement benefit benefit plan adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax	(794.7)	(1,182.3)	(794.7)	(1,182.3)	(823.8)	(1,226.0)
Other comprehensive income (loss) before reclassifications, net of tax			0	0
Amounts reclassified from accumulated other comprehensive loss, net of tax			29.1	43.7
Other comprehensive income (loss), net of tax			29.1	43.7
Accumulated currency translation adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax	23.1	(19.2)	23.1	(19.2)	8.8	0.5
Other comprehensive income (loss) before reclassifications, net of tax			14.3	(19.7)
Amounts reclassified from accumulated other comprehensive loss, net of tax			0	0
Other comprehensive income (loss), net of tax			14.3	(19.7)
Net unrealized gains (losses) on cash flow hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax	(4.0)	4.4	(4.0)	4.4	(2.7)	0.2
Other comprehensive income (loss) before reclassifications, net of tax			(1.0)	4.6
Amounts reclassified from accumulated other comprehensive loss, net of tax			(0.3)	(0.4)
Other comprehensive income (loss), net of tax			(1.3)	4.2
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net of tax	14.5	21.9	28.8	43.3
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension and other postretirement benefit benefit plan adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of prior service credit	(3.4)	(3.4)	(6.6)	(6.7)
Amortization of net actuarial loss	25.8	37.2	51.4	74.6
Total before tax	22.4	33.8	44.8	67.9
Tax (expense) benefit	(7.9)	(12.0)	(15.7)	(24.2)
Net of tax	14.5	21.8	29.1	43.7
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net unrealized gains (losses) on cash flow hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Sales	0.8	(0.9)	1.0	(0.5)
Cost of Sales	(1.7)	1.0	(2.4)	(0.2)
Total before tax	(0.9)	0.1	(1.4)	(0.7)
Tax (expense) benefit	0.9	0	1.1	0.3
Net of tax	$ 0	$ 0.1	$ (0.3)	$ (0.4)