Shareholders' Equity (Deficit): Dividends and Repurchase of Common Stock (Details) - USD ($)					12 Months Ended
	Aug. 16, 2017	Jul. 19, 2017	May 13, 2015	Apr. 15, 2015	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Repurchase of Common Stock
Aggregate purchase price of shares repurchased (in dollars)					$ 49,902,500	$ 1,573,900	$ 74,853,700
Dividends
Cash dividends declared and paid (in dollars per share)					$ 0.43	$ 0.37	$ 0.27
Aggregate quarterly cash dividends declared and paid					$ 1,765,000	$ 1,526,800	$ 1,228,200
Tender Offer
Repurchase of Common Stock
Shares authorized for repurchase		400,000		875,000
Purchase of stock, price per share		$ 124.48		$ 84.72
Number of shares repurchased	400,000		875,000
Aggregate purchase price of shares repurchased (in dollars)	$ 49,900,000		$ 74,300,000
Common Stock Repurchase Program
Repurchase of Common Stock
Number of shares repurchased						17,194	6,518
Aggregate purchase price of shares repurchased (in dollars)						$ 1,600,000	$ 600,000
Aggregate purchase price per share of shares repurchased (in dollars per share)						$ 91.54	$ 90.85
Number of additional shares that can be repurchased					142,988