Earnings Per Share Narrative (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 26, 2014	Sep. 27, 2013	Sep. 28, 2012
Class of Stock [Line Items]
Effect of stock dividend	$ 0	$ 0	$ 0
Dividend equivalent rights	4,612	4,007	2,709
Tax on payments of dividend equivalent rights	306	91	26
Common Stock
Class of Stock [Line Items]
Stock dividend paid to company stockholders				5.00%	5.00%	5.00%
Effect of stock dividend	$ 520	$ 450	$ 414
Increase in number of shares subject to outstanding stock options	5.00%	5.00%	5.00%