Summary of Significant Accounting Policies New Accounting Pronouncements and Changes in Accounting Principals (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 02, 2017	Jul. 02, 2017	Jul. 03, 2016	Jan. 01, 2017
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment of new accounting principle in period of adoption				$ (0.2)
Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income tax expense (benefit)	$ (1.0)	$ (1.8)
Excess tax benefit from stock-based compensation, Operating Activities			$ 1.4
Excess tax benefit from stock-based compensation, Financing Activities			$ 1.4