Shareowners' Equity (Details 1) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ (1,538.8)	$ (1,334.6)	$ (948.0)
Other comprehensive (loss) income before reclassifications, net of tax	260.0	(262.6)	(420.5)
Amounts reclassified from accumulated other comprehensive loss, net of tax	99.6	58.4	33.9
Other comprehensive income (loss)	359.6	(204.2)	(386.6)
Balance at end of period	(1,179.2)	(1,538.8)	(1,334.6)
Pension and other postretirement benefit plan adjustments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(1,239.8)	(1,097.1)	(909.4)
Other comprehensive (loss) income before reclassifications, net of tax	215.2	(216.5)	(257.3)
Amounts reclassified from accumulated other comprehensive loss, net of tax	97.6	73.8	69.6
Other comprehensive income (loss)	312.8	(142.7)	(187.7)
Balance at end of period	(927.0)	(1,239.8)	(1,097.1)
Accumulated currency translation adjustments, net of tax [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(294.9)	(252.4)	(52.5)
Other comprehensive (loss) income before reclassifications, net of tax	57.2	(42.5)	(199.9)
Amounts reclassified from accumulated other comprehensive loss, net of tax	0.0	0.0	0.0
Other comprehensive income (loss)	57.2	(42.5)	(199.9)
Balance at end of period	(237.7)	(294.9)	(252.4)
Net unrealized gains (losses) on cash flow hedges, net of tax [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(4.1)	14.9	13.9
Other comprehensive (loss) income before reclassifications, net of tax	(12.3)	(3.6)	36.7
Amounts reclassified from accumulated other comprehensive loss, net of tax	2.0	(15.4)	(35.7)
Other comprehensive income (loss)	(10.3)	(19.0)	1.0
Balance at end of period	(14.4)	(4.1)	14.9
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	0.0	0.0	0.0
Other comprehensive (loss) income before reclassifications, net of tax	(0.1)	0.0	0.0
Amounts reclassified from accumulated other comprehensive loss, net of tax	0.0	0.0	0.0
Other comprehensive income (loss)	(0.1)	0.0	0.0
Balance at end of period	$ (0.1)	$ 0.0	$ 0.0