Earnings per Share Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Sep. 24, 2016	Jun. 25, 2016	Mar. 26, 2016	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Earnings Per Share [Abstract]
Net income attributable to Dunkin' Brands-basic and diluted	$ 195,492	$ 52,246	$ 55,704	$ 47,467	$ 56,120	$ 52,712	$ 49,590	$ 37,154	$ 350,909	$ 195,576	$ 105,227
Weighted average number of common shares - basic and diluted:
Common-basic (in shares)									90,857,168	91,568,942	96,045,232
Common-diluted (in shares)									92,231,436	92,538,282	97,131,674
Earnings Per Share, Basic and Diluted [Abstract]
Common-basic (in dollars per share)	$ 2.17	$ 0.58	$ 0.61	$ 0.52	$ 0.61	$ 0.58	$ 0.54	$ 0.41	$ 3.86	$ 2.14	$ 1.10
Common-diluted (in dollars per share)	$ 2.13	$ 0.57	$ 0.60	$ 0.51	$ 0.61	$ 0.57	$ 0.54	$ 0.40	$ 3.80	$ 2.11	$ 1.08