Earnings per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income attributable to Dunkin' Brands-basic and diluted	$ 59,622	$ 60,498	$ 111,945	$ 110,650
Weighted average number of common shares:
Common-basic (in shares)	82,778,329	82,869,232	82,699,550	84,660,208
Common-diluted (in shares)	83,696,721	84,113,681	83,564,388	85,995,475
Earnings (loss) per common share:
Common-basic (in dollars per share)	$ 0.72	$ 0.73	$ 1.35	$ 1.31
Common-diluted (in dollars per share)	$ 0.71	$ 0.72	$ 1.34	$ 1.29