Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Tax on (loss) gain on derivative instruments	$ 0.6	$ (4.1)	$ (6.5)	$ (7.1)
Tax on reclassifications on derivative instruments	(1.3)	(2.1)	4.0	(9.8)
Tax on foreign currency adjustments	0	(2.4)	(3.1)	1.8
Tax on benefit plans	$ (0.2)	$ (0.2)	$ (0.2)	$ (0.7)