Earnings per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to Dunkin' Brands-basic and diluted	$ 52,113	$ 52,323
Weighted average number of common shares:
Common-basic (in shares)	82,675,487	82,620,759
Common-diluted (in shares)	83,222,485	83,432,042
Earnings (loss) per common share:
Common-basic (in dollars per share)	$ 0.63	$ 0.63
Common-diluted (in dollars per share)	$ 0.63	$ 0.63