Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 15, 2017	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Contingency [Line Items]
Effective income tax rate reconciliation, percent		14.50%	65.50%	42.90%	68.70%
Income tax examination, penalties and interest expense	$ 163.6						$ 24.7	$ 40.2	$ 61.5	$ 37.2
Income tax benefit		$ (7.7)				$ 2.4
Tax expense in connection with Transition Toll Tax						17.5
Foreign earnings						1,200.0
Belgium Taxing Authority
Income Tax Contingency [Line Items]
Income tax expense for remeasurement of deferred tax assets						24.1
Tax benefit for remeasurement of tax liabilities						$ 33.2