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. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017
Revenue from contract with customer	$ 298,827	$ 302,159	$ 338,258	$ 302,376	$ 240,571	$ 214,780	$ 299,722	$ 299,527	$ 1,241,620	$ 1,054,600
Total revenue									1,241,620	1,054,600	$ 1,080,177
Cost of revenue	45,960	39,690	36,575	38,629	31,259	34,383	31,027	30,893	160,854	127,562	118,529
Gross margin	252,867	262,469	301,683	263,747	209,312	180,397	268,695	268,634	1,080,766	927,038	961,648
Income/(loss) before taxes and controlling interest	56,251	41,800	110,002	74,254	17,853	(5,808)	87,782	96,547	282,307	196,374	255,145
Net income attributable to Dolby Laboratories, Inc.	$ 43,918	$ 39,574	$ 73,440	$ 98,219	$ 26,716	$ 3,116	$ 65,216	$ (53,302)	$ 255,151	$ 41,746	$ 206,481
Net Income Per Share:
Basic (usd per share)	$ 0.44	$ 0.39	$ 0.72	$ 0.96	$ 0.26	$ 0.03	$ 0.63	$ (0.52)	$ 2.51	$ 0.40	$ 2.03
Diluted (usd per share)	$ 0.43	$ 0.38	$ 0.70	$ 0.93	$ 0.25	$ 0.03	$ 0.61	$ (0.52)	$ 2.44	$ 0.39	$ 2.00
Weighted-average shares outstanding:
Basic (shares)	100,481	101,218	102,141	102,677	103,349	103,836	103,771	102,552	101,629	103,377	101,784
Diluted (shares)	102,945	103,717	104,587	106,130	106,794	106,950	107,001	102,552	104,572	106,978	103,286
Licensing
Revenue from contract with customer	$ 264,796	$ 271,897	$ 310,308	$ 260,279	$ 214,699	$ 183,771	$ 272,135	$ 270,172	$ 1,107,280	$ 940,777	$ 965,864
Product and service [Member]
Revenue from contract with customer	$ 34,031	$ 30,262	$ 27,950	$ 42,097	$ 25,872	$ 31,009	$ 27,587	$ 29,355