Subsequent Events (Details) - USD ($)		1 Months Ended	12 Months Ended
	Jan. 16, 2020	Dec. 31, 2019	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Subsequent Events
Borrowing from Line of Credit for Tender Offer			$ 18,800,000	$ 7,300,000	$ 51,900,000
2020 Tender Offer | Subsequent Event
Subsequent Events
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
Borrowing from Line of Credit for Tender Offer	$ 19,200,000