Shareholders' Equity (Deficit): Dividends and Repurchase of Common Stock (Details) - USD ($)					1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 15, 2020	Apr. 29, 2020	Jan. 29, 2020	Jan. 16, 2020	Dec. 31, 2019	Mar. 28, 2020	Mar. 30, 2019	Sep. 26, 2020	Sep. 28, 2019
Repurchase of Common Stock
Aggregate purchase price of shares repurchased (in dollars)						$ 48,987,500	$ 24,028,100
Borrowing from Line of Credit for Tender Offer								$ 46,600,000	$ 18,800,000
Dividends
Cash dividends declared and paid (in dollars per share)	$ 0.25	$ 0.05	$ 0.25
2020 Tender Offer
Repurchase of Common Stock
Shares authorized for repurchase per tender offer					300,000
Price per share of common stock per tender offer					$ 163.00
Number of shares repurchased				300,000
Purchase price of shares per tender offer				$ 49,000,000.0
Borrowing from Line of Credit for Tender Offer				$ 19,200,000
Common Stock Repurchase Program
Repurchase of Common Stock
Number of additional shares that can be repurchased								130,604