Income Taxes - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Dec. 22, 2018	Mar. 29, 2019	Mar. 30, 2018	Mar. 29, 2019	Mar. 30, 2018
Income Tax Disclosure [Abstract]
Income tax expense for the measurement period	$ 144.4
Income Tax Expense (Benefit)					$ 69.4
Change in enacted tax rate, amount					16.9
Charges and benefit from valuation allowance, amount					$ 52.5
Provisional remeasurement income tax expense discrete benefit, deferred tax balances	14.3	$ 37.4	$ 40.6
Estimated valuation allowance	$ 104.2
Effective income tax rate (percent)		(7.10%)	106.60%	7.30%	188.50%
Decrease in unrecognized tax benefits is reasonably possible		$ 21.2		$ 21.2