Earnings Per Share Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 27, 2018	Sep. 28, 2017	Sep. 29, 2016
Class of Stock [Line Items]
Stock dividend paid to company stockholders				5.00%	5.00%	5.00%
Effect of stock dividend	$ 0	$ 0	$ 0
Increase in number of shares subject to outstanding stock options	5.00%	5.00%
Dividend equivalent rights	$ 8,696	$ 7,655	6,258
Tax on payments of dividend equivalent rights	0	0	435
Common Stock
Class of Stock [Line Items]
Effect of stock dividend	$ 671	$ 644	$ 609