Shareholders' Equity (Deficit): Dividends and Repurchase of Common Stock (Details) - USD ($)				1 Months Ended	12 Months Ended
	Mar. 28, 2019	Aug. 16, 2017	Jul. 19, 2017	Feb. 28, 2019	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Repurchase of Common Stock
Aggregate purchase price of shares repurchased (in dollars)					$ 24,028,100	$ 1,846,400	$ 49,902,500
Dividends
Cash dividends declared and paid (in dollars per share)					$ 0.90	$ 0.56	$ 0.43
Aggregate quarterly cash dividends declared and paid					$ 3,449,100	$ 2,169,900	$ 1,765,000
2019 Tender Offer
Repurchase of Common Stock
Shares authorized for repurchase per tender offer				150,000
Price per share of common stock per tender offer				$ 159.63
Number of shares repurchased	150,000
Purchase price of shares per tender offer	$ 24,000,000
Tender Offer
Repurchase of Common Stock
Shares authorized for repurchase per tender offer			400,000
Price per share of common stock per tender offer			$ 124.48
Number of shares repurchased		400,000
Aggregate purchase price of shares repurchased (in dollars)		$ 49,900,000
Common Stock Repurchase Program
Repurchase of Common Stock
Purchase of stock, price per share						$ 149.10
Number of shares repurchased						12,384
Aggregate purchase price of shares repurchased (in dollars)						$ 1,800,000
Number of additional shares that can be repurchased					130,604