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Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2019	Sep. 30, 2018
Income Taxes
Effective tax rate (as a percent)			(71.80%)	0.50%
Net benefit from Tax Cuts and Jobs Acts of 2017			$ 41.7
Benefit from change in uncertain tax positions in US and Canada			33.8
Benefit from income tax credits and incentives			21.6
Amount of tax expense arising from a business combination related to non-deductible goodwill			33.9
Amount of uncertain tax positions for future years	$ 26.2
Federal statutory rate (as a percent)		35.00%			21.00%
Blended statutory rate (as a percentage)						24.50%
Provisional amount related to remeasurement of deferred tax balance		$ 36.1
Provisional amount of tax benefit related to releasing of deferred tax liability		77.0
Provisional amount of income tax expense related to transition tax on foreign subsidiaries		$ 71.4
Gross book-tax differences from non-U.S. subsidiaries			$ 1,700.0

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Percentage of domestic federal statutory blended tax rate applicable to pretax income (loss).

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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