Per Share Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 25, 2020	Dec. 27, 2019
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income attributable to Dolby Laboratories, Inc.	$ 135,198	$ 48,753
Weighted average shares outstanding-basic (in shares)	100,716	100,336
Potential common shares from options to purchase common stock (in shares)	1,767	1,711
Potential common shares from restricted stock units (in shares)	1,309	1,020
Potential common shares from ESPP (in shares)	84	11
Weighted average shares outstanding-diluted (in shares)	103,876	103,078
Net income per share attributable to Dolby Laboratories, Inc. - Basic (in usd per share)	$ 1.34	$ 0.49
Net income per share attributable to Dolby Laboratories, Inc. - Diluted (in usd per share)	$ 1.30	$ 0.47
Employee Stock Option [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations (in shares)	39	2,623
Restricted Stock Units (RSUs) [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations (in shares)	162	8
Employee Stock Purchase Plan [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations (in shares)	1	3