Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2017
Effect Of Tax Cuts And Jobs Act Of 2017 Accounting Incomplete Provisional [Abstract]
Corporate income tax rate	21.00%		35.00%
Reduction in net deferred tax assets resulting from revaluation using new tax rate		$ (33.1)
Reduction in valuation allowance due to Tax Cuts and Jobs Act of 2017		(33.1)
Amount of tax expense related to the revaluation of net deferred tax assets under the Tax Act		$ 0.0