Income Taxes - Narrative (Details) - USD ($) $ in Millions			3 Months Ended
	Dec. 22, 2017	Dec. 21, 2017	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Income Tax Disclosure [Abstract]
U.S. statutory rate	21.00%	35.00%	21.00%	35.00%
Blended effective income tax rate			24.53%
Effective income tax rate			179.40%	16.70%
Effective income tax rate reconciliation, effect of tax cuts and jobs act of 2017, amount			$ 479.7
Effective income tax rate reconciliation, effect of tax cuts and jobs act of 2017, percent			161.10%
Effective income tax rate reconciliation, change in enacted tax rate, amount			$ 94.2
Effective income tax rate reconciliation, repatriation of foreign earnings, amount			385.5
Income taxes payable, repatriation of foreign earnings			381.2
Tax adjustments, settlements, and unusual provisions			94.2
Deferred tax liabilities, deferred expense			60.5
Deferred tax assets, deferred income			60.5
Gross unrecognized tax benefits			27.6		$ 31.1
Accrued interest and penalties related to unrecognized tax benefits			3.9		$ 4.0
Reasonably possible amount of reduction in gross unrecognized tax benefits for the next twelve months			7.4
Reasonably possible amount of net reduction to income tax provision if unrecognized tax benefits were recognized			$ 5.6
Earliest open year for income tax examinations, U.S. federal			2014
Earliest open tax year for income tax examinations, state, local and non-U.S.			2003