Revenues Estimated revenue recognition (Details) $ in Thousands	Jun. 27, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	$ 21,430
2018 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	1,093
2019 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	2,107
2020 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	1,983
2021 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	1,773
2022 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	1,665
Thereafter [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	11,360
Development agreements and unopened restaurants [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred franchise revenue expected to be recognized	$ 1,449