Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 30, 2017	Dec. 31, 2016	Jun. 30, 2018
Operating Loss Carryforwards [Line Items]
Reasonable estimate of income tax expense			$ 35.8
Provisional income tax expense (benefit)			(64.7)
Tax benefit attributable to income taxes payable and deferred tax assets (liabilities)			(14.5)
Transition tax expense (benefit)			115.0
Transition tax as a result of Tax Cuts and Jobs Act, liability, noncurrent	$ 95.0		$ 95.0
Effective income tax rate	37.11%	34.87%	34.71%	35.09%
Effective tax rates, net tax expense (benefit)			$ (79.2)
Excess tax benefits of equity-based compensation and tax law changes in foreign jurisdictions	$ 8.1		14.8
Unrecognized tax benefits	16.2		16.2
Liability recorded for interest and penalties related to unrecognized tax benefits	$ 11.5		$ 11.5
Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Blended statutory tax rate					28.00%