Segment information - Depreciation and Amortization by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Segment Reporting Information [Line Items]
Total depreciation and amortization	$ 20,084	$ 20,458	$ 20,556
Corporate and Other
Segment Reporting Information [Line Items]
Total depreciation and amortization	8,384	8,707	7,902
Operating segments
Segment Reporting Information [Line Items]
Total depreciation and amortization	11,700	11,751	12,654
Operating segments | Dunkin Donuts | United States
Segment Reporting Information [Line Items]
Total depreciation and amortization	11,296	11,378	12,229
Operating segments | Dunkin Donuts | International
Segment Reporting Information [Line Items]
Total depreciation and amortization	31	27	7
Operating segments | Baskin Robbins | United States
Segment Reporting Information [Line Items]
Total depreciation and amortization	320	272	358
Operating segments | Baskin Robbins | International
Segment Reporting Information [Line Items]
Total depreciation and amortization	$ 53	$ 74	$ 60