Goodwill and Intangible Assets - Components of Company's Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill (not subject to amortization)	$ 2,935.8	$ 2,989.0	$ 2,965.1	[1]
Intangible assets:
Customer relationships, noncompete agreements and other	759.4	773.5	764.6
Accumulated amortization	(329.0)	(324.8)	(292.2)
Intangible assets, net (definite-lived)	430.4	448.7	472.4
Trademarks and tradenames (indefinite-lived)	128.5	131.6	130.0
Total intangible assets, net	$ 558.9	$ 580.3	$ 602.4

[1] Restated to reflect (1) the current-year changes in the presentation of our UGI International and Midstream & Marketing reportable segments and (2) the adoption of new accounting guidance related to debt issuance costs (see Note 2).