Summary of Refranchsing and Franchise Acquisitions Summary of refranchising (Details) $ in Thousands	4 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($) restaurant	Dec. 31, 2019 USD ($) restaurant	Jan. 01, 2019 USD ($) restaurant	Jan. 02, 2018 USD ($) restaurant	Jan. 02, 2019 USD ($)
Franchisor Disclosure [Line Items]
Assets Held-For-Sale, Other Property And Equipment, Not Part of Disposal Group, Adjustment	$ 6,800	$ 6,800
Assets held for sale	8,411	$ 8,411	$ 14,794		$ 14,794
Company-operated restaurants sold to franchisees | restaurant		31	0	5
Proceeds from Divestiture of Businesses		$ 7,310	$ 0	$ 2,192
Net assets sold (primarily furniture, fixtures and equipment)		(4,952)	0	(1,261)
Goodwill related to the company-operated restaurants sold to franchisees		(6,078)	0	(247)
Allocation to Deferred Franchise Fees		(771)	0	0
(Unfavorable)/favorable lease assets/liabilities		(50)	0	(548)
Other costs related to the sale of company-operated restaurants		(123)	0	(5)
Gain on sale of company-operated restaurants		(4,664)	0	131
Favorable lease assets	10,827	10,827	18,507
Unfavorable Leasehold Interests Noncurrent, Accrual Adjustment			600
Assets Held-For-Sale, Other Property And Equipment, Not Part of Disposal Group	4,025	4,025	2,023
Goodwill	4,386	4,386	0
Assets Held-For-Sale, Goodwill, Not Part of Disposal Group	14,800	14,800
Assets And Leaseback Held-For-Sale, Not Part of Disposal Group	0	0	$ 12,771
Sale of company-operated restaurants
Franchisor Disclosure [Line Items]
Favorable lease assets	1,200	1,200		100
Unfavorable Leasehold Interests Noncurrent	$ 1,300	1,300		$ 600
18 Stores Sold [Member]
Franchisor Disclosure [Line Items]
Company-operated restaurants sold to franchisees | restaurant	18
Assets Held-For-Sale, Goodwill, Not Part of Disposal Group	$ 6,100	$ 6,100