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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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