Per Share Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income attributable to Dolby Laboratories, Inc.	$ 50,092	$ 83,145	$ 70,631	$ (81,622)	$ 21,795	$ 76,043	$ 50,590	$ 53,374	$ 122,246	$ 201,802	$ 185,860
Weighted Average Number of Shares Outstanding, Basic	103,349	103,836	103,771	102,552	101,959	101,905	101,787	101,483	103,377	101,784	100,717
Potential common shares from options to purchase Class A and Class B common stock									2,370	1,098	1,013
Potential common shares from restricted stock units									1,231	404	694
Weighted Average Number of Shares Outstanding, Diluted	106,794	106,950	107,001	102,552	103,530	104,222	103,883	103,876	106,978	103,286	102,424
Basic (usd per share)	$ 0.48	$ 0.80	$ 0.68	$ (0.80)	$ 0.21	$ 0.75	$ 0.50	$ 0.53	$ 1.18	$ 1.98	$ 1.85
Net income per share attributable to Dolby Laboratories, Inc. - Diluted	$ 0.47	$ 0.78	$ 0.66	$ (0.80)	$ 0.21	$ 0.73	$ 0.49	$ 0.51	$ 1.14	$ 1.95	$ 1.81
Employee Stock Option [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations									1,043	160	2,971
Restricted Stock Units [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations									6	0	30