New Accounting Guidance (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess tax benefits recognized under new accounting standard	$ 17.6
Accounting Standards Update 2016-09 | Early Adoption, Effect | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment related to adoption of new accounting standard		$ 8.8
Accounting Standards Update 2015-03 | Other Noncurrent Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of debt issuance cost with (decrease) to assets and decrease to liabilities			$ (17.0)
Accounting Standards Update 2015-03 | Other Noncurrent Assets | Discontinued Operations
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of debt issuance cost with (decrease) to assets and decrease to liabilities			(9.6)
Accounting Standards Update 2015-03 | Long-term Debt
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of debt issuance cost with (decrease) to assets and decrease to liabilities			17.0
Accounting Standards Update 2015-03 | Other Noncurrent Liabilities | Discontinued Operations
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of debt issuance cost with (decrease) to assets and decrease to liabilities			$ 9.6