Shareholders' Equity (Deficit): Dividends and Repurchase of Common Stock (Details) - USD ($)			12 Months Ended
	May 13, 2015	Apr. 15, 2015	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Repurchase of Common Stock
Aggregate purchase price of shares repurchased (in dollars)			$ 1,573,900	$ 74,853,700	$ 11,564,800
Dividends
Cash dividends declared and paid (in dollars per share)			$ 0.37	$ 0.27	$ 0.23
Aggregate quarterly cash dividends declared and paid			$ 1,500,000	$ 1,200,000	$ 1,200,000
Special cash dividend approved by Board of Directors (in dollars per share)					$ 5.00
Total special dividend in cash					$ 25,800,000
Tender Offer
Repurchase of Common Stock
Shares authorized for repurchase		875,000
Purchase Of Stock Price Per Share		$ 84.72
Number of shares repurchased	875,000
Aggregate purchase price of shares repurchased (in dollars)	$ 74,300,000
Common Stock Repurchase Program
Repurchase of Common Stock
Number of shares repurchased			17,194	6,518	166,030
Aggregate purchase price of shares repurchased (in dollars)			$ 1,600,000	$ 600,000	$ 11,600,000
Aggregate purchase price per share of shares repurchased (in dollars per share)			$ 91.54	$ 90.85	$ 69.65
Number of additional shares that can be repurchased			142,988