Benefit Plans and Other Postretirement Benefits, Defined contribution plans (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Benefit Plans and Other Postretirement Benefits
Contributions to U.S. defined contribution plans by the Company, maximum percentage of eligible compensation	6.00%	5.00%
Matching contributions to U.S. defined contribution plans by the Company		$ 8.6	$ 6.9	$ 5.0