Per Share Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 28, 2018	Dec. 29, 2017
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income/(loss) attributable to Dolby Laboratories, Inc.	$ 98,219	$ (53,302)
Weighted average shares outstanding-basic (in shares)	102,677	102,552
Potential common shares from options to purchase common stock (in shares)	2,251	0
Potential common shares from restricted stock units (in shares)	1,202	0
Weighted average shares outstanding-diluted (in shares)	106,130	102,552
Net income per share attributable to Dolby Laboratories, Inc. - Basic (in usd per share)	$ 0.96	$ (0.52)
Net income per share attributable to Dolby Laboratories, Inc. - Diluted (in usd per share)	$ 0.93	$ (0.52)
Employee Stock Option [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations (in shares)	1,583	2,424
Restricted Stock Units (RSUs) [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Anti-dilutive securities, excluded from calculations (in shares)	10	1,358