Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax	$ (1,015.4)	$ (760.6)	$ (1,015.4)	$ (760.6)	$ (1,040.7)	$ (948.0)	$ (775.6)	$ (817.7)
Other comprehensive income (loss) before reclassifications, net of tax	21.3	(2.1)	(95.7)	11.2
Amounts reclassified from accumulated other comprehensive loss, net of tax	4.0	17.1	28.3	45.9
Other comprehensive income (loss), net of tax	25.3	15.0	(67.4)	57.1
Pension and other postretirement benefit plan adjustments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax	(857.2)	(780.1)	(857.2)	(780.1)	(874.6)	(909.4)	(794.7)	(823.8)
Other comprehensive income (loss) before reclassifications, net of tax	0.0	0.0	0.0	0.0
Amounts reclassified from accumulated other comprehensive loss, net of tax	17.4	14.6	52.2	43.7
Other comprehensive income (loss), net of tax	17.4	14.6	52.2	43.7
Accumulated currency translation adjustments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax	(185.7)	24.3	(185.7)	24.3	(213.1)	(52.5)	23.1	8.8
Other comprehensive income (loss) before reclassifications, net of tax	27.4	1.2	(133.2)	15.5
Amounts reclassified from accumulated other comprehensive loss, net of tax	0.0	0.0	0.0	0.0
Other comprehensive income (loss), net of tax	27.4	1.2	(133.2)	15.5
Net unrealized gains (losses) on cash flow hedges [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss), net of tax	27.5	(4.8)	27.5	(4.8)	$ 47.0	$ 13.9	$ (4.0)	$ (2.7)
Other comprehensive income (loss) before reclassifications, net of tax	(6.1)	(3.3)	37.5	(4.3)
Amounts reclassified from accumulated other comprehensive loss, net of tax	(13.4)	2.5	(23.9)	2.2
Other comprehensive income (loss), net of tax	$ (19.5)	$ (0.8)	$ 13.6	$ (2.1)