Fair Value Measurements (Schedule of Nonrecurring Fair Value Measurements) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2016
Long Lived Assets Held-for-sale [Line Items]
Write-down of long-lived assets associated with restructuring			$ 69.2	$ 0.0	$ 40.2
Equity method investment impairment charge		$ 79.5	79.5	0.0	$ 0.0
Continuing Operations
Long Lived Assets Held-for-sale [Line Items]
Write-down of long-lived assets associated with restructuring	[1]		45.7	0.0
Discontinued Operations
Long Lived Assets Held-for-sale [Line Items]
Write-down of long-lived assets held for sale	[1]		6.3	$ 913.5
Fair Value, Measurements, Nonrecurring | Continuing Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Continuing operations	[1]					$ 1.4
Fair Value, Measurements, Nonrecurring | Discontinued Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Discontinued operations	[1]					11.0
Level 1 | Fair Value, Measurements, Nonrecurring | Continuing Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Continuing operations	[1]					0.0
Level 1 | Fair Value, Measurements, Nonrecurring | Discontinued Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Discontinued operations	[1]					0.0
Level 2 | Fair Value, Measurements, Nonrecurring | Continuing Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Continuing operations	[1]					0.0
Level 2 | Fair Value, Measurements, Nonrecurring | Discontinued Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Discontinued operations	[1]					0.0
Level 3 | Fair Value, Measurements, Nonrecurring | Continuing Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Continuing operations	[1]					1.4
Level 3 | Fair Value, Measurements, Nonrecurring | Discontinued Operations
Long Lived Assets Held-for-sale [Line Items]
Plant and Equipment – Discontinued operations	[1]					$ 11.0
Abdullah Hashim Industrial Gases & Equipment Co., Ltd.
Long Lived Assets Held-for-sale [Line Items]
Equity method investment impairment charge	[2]		$ 79.5
Abdullah Hashim Industrial Gases & Equipment Co., Ltd. | Fair Value, Measurements, Nonrecurring
Long Lived Assets Held-for-sale [Line Items]
Investment in Equity Affiliate	[2]	68.5
Abdullah Hashim Industrial Gases & Equipment Co., Ltd. | Level 1 | Fair Value, Measurements, Nonrecurring
Long Lived Assets Held-for-sale [Line Items]
Investment in Equity Affiliate	[2]	0.0
Abdullah Hashim Industrial Gases & Equipment Co., Ltd. | Level 2 | Fair Value, Measurements, Nonrecurring
Long Lived Assets Held-for-sale [Line Items]
Investment in Equity Affiliate	[2]	0.0
Abdullah Hashim Industrial Gases & Equipment Co., Ltd. | Level 3 | Fair Value, Measurements, Nonrecurring
Long Lived Assets Held-for-sale [Line Items]
Investment in Equity Affiliate	[2]	$ 68.5

[1] We assessed the recoverability of the carrying value of assets associated with the EfW discontinued operation, including the air separation unit within continuing operations of our Industrial Gases – EMEA segment. We based our estimates primarily on an orderly liquidation valuation which resulted in losses for the difference between the orderly liquidation value and net book value of the assets as of 31 December 2016 during fiscal year 2017. There have been no significant updates to our estimates as of 30 September 2017. For additional information, see Note 3, Discontinued Operations, and Note 5, Business Restructuring and Cost Reduction Actions.

[2] We assessed the recoverability of the carrying value of our equity investment in AHG. We estimated the fair value of our investment using weighting of the results of the income and market approaches. An impairment loss was recognized for the difference between the carrying amount and the fair value of the investment as of 30 June 2017. There have been no updates to our estimates as of 30 September 2017. For additional information, see Note 8, Summarized Financial Information of Equity Affiliates.