Notes Receivable - Summary of Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 25, 2016
Notes receivable
Balance at the beginning of the period	$ 2,759
Balance at the end of the period	1,047	$ 2,759
Reserve for franchisee notes receivable
Notes receivable
Balance at the beginning of the period	2,759	3,653
Recovered from costs and expenses	(1,715)	(250)
Additions (deductions) including or net of notes written off	3	(644)
Balance at the end of the period	$ 1,047	$ 2,759