Selected Quarterly Financial Data (unaudited) (Schedule Of Selected Quarterly Financial 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
Quarterly Financial Data [Abstract]
Licensing	$ 240,122	$ 286,325	$ 273,143	$ 258,016	$ 213,370	$ 278,106	$ 241,617	$ 232,699	$ 1,057,606	$ 965,792	$ 917,032
Products	20,689	26,265	22,665	24,933	23,797	22,569	20,713	28,211	94,552	95,290	90,543
Services	4,514	4,857	5,547	4,848	4,881	4,990	5,144	5,357	19,766	20,372	18,163
Total revenue	265,325	317,447	301,355	287,797	242,048	305,665	267,474	266,267	1,171,924	1,081,454	1,025,738
Cost of revenue	31,960	34,465	30,959	30,876	29,238	32,125	26,977	29,967	128,260	118,307	108,982
Gross margin	233,365	282,982	270,396	256,921	212,810	273,540	240,497	236,300	1,043,664	963,147	916,756
Income before taxes and controlling interest	41,960	96,590	89,483	84,834	26,491	96,303	66,194	67,656	312,867	256,644	235,904
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
Net Income Per Share:
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
Diluted (usd per share)	$ 0.47	$ 0.78	$ 0.66	$ (0.80)	$ 0.21	$ 0.73	$ 0.49	$ 0.51	$ 1.14	$ 1.95	$ 1.81
Weighted-average shares outstanding:
Basic (shares)	103,349	103,836	103,771	102,552	101,959	101,905	101,787	101,483	103,377	101,784	100,717
Diluted (shares)	106,794	106,950	107,001	102,552	103,530	104,222	103,883	103,876	106,978	103,286	102,424