Commitments and Contingencies (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 29, 2020 USD ($) item	Sep. 29, 2020 USD ($) item restaurant	Dec. 31, 2019 USD ($)
Commitments and Contingencies
Estimated cost to complete capital project commitments (in dollars)	$ 110.5	$ 110.5	$ 119.0
Number of continuing construction of restaurants. \| restaurant		18
Estimated cost of completion		$ 46.3
Number of suppliers providing most of the company's beef \| item	3	3
Lease Agreements
Commitments and Contingencies
Number of leases guarantees entity contingently liable \| item		7
Lease Agreements \| Maximum
Commitments and Contingencies
Contingently liable amount	$ 13.3	$ 13.3	$ 13.9

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
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-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant