Goodwill and Intangible Assets - Components of Company's Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill (not subject to amortization)	$ 2,885.1	$ 2,871.0	$ 2,834.0
Intangible assets:
Customer relationships, noncompete agreements and other	717.3	706.4	692.6
Trademarks and tradenames (not subject to amortization)	132.0	131.3	128.4
Gross carrying amount	849.3	837.7	821.0
Accumulated amortization	(259.0)	(227.1)	(212.4)
Intangible assets, net	$ 590.3	$ 610.6	$ 608.6