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Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Income Taxes
Effective tax rate (as a percent)	(106.70%)	(60.90%)
Net benefit from Tax Cuts and Jobs Acts of 2017		$ 41.7
Benefit from change in uncertain tax positions in US and Canada		$ 11.2
Federal statutory rate (as a percent)	21.00%	24.50%	35.00%
Valuation allowance on foreign tax credits	$ 38.1
Gross book-tax differences from non-U.S. subsidiaries	$ 1,800.0

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Amount of gross book tax differences of foreign subsidiaries intended to be permanently reinvested outside the country of domicile.

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

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

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