Interim Condensed Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Total Dolby Laboratories,Inc.[Member]	Controlling Interest [Member]	Class A Common Stock [Member] Common Stock [Member]	Class A Common Stock [Member] Additional Paid-In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Outstanding		101
Beginning balance at Sep. 30, 2016	$ 1,978,735		$ 42,032	$ 1,938,320	$ (10,197)	$ 1,970,256	$ 8,479
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	53,574			53,374		53,374	200
Translation adjustments, net of tax of $829 and $(64), respectively	(7,724)				(7,463)	(7,463)	(261)
Unrealized gains (losses) on available-for-sale securities, net of tax of $(327) and $(98), respectively	(2,019)				(2,019)	(2,019)
Distributions to controlling interest	(2,094)						(2,094)
Stock-based compensation expense	17,215		17,215			17,215
Shares repurchased (in shares)								1
Repurchase of common stock	(25,001)		(25,000)			(25,001)
Cash dividends declared and paid on common stock	(14,216)			(14,216)		(14,216)
Tax benefit/(deficiency) from the stock incentive plans	2,853		2,853			2,853
Common stock issued under employee stock plans	13,991		13,990			13,991		$ 1
Tax withholdings on vesting of restricted stock	(14,656)					(14,656)		(1)	$ (14,655)
Ending balance at Dec. 30, 2016	2,000,658		36,435	1,977,478	(19,679)	1,994,334	6,324
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Outstanding		100
Shares, Outstanding		101
Beginning balance at Sep. 29, 2017	2,143,842		61,331	2,083,063	(7,753)	2,136,742	7,100
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(81,478)			(81,622)		(81,622)	144
Translation adjustments, net of tax of $829 and $(64), respectively	1,218				1,224	1,224	(6)
Unrealized gains (losses) on available-for-sale securities, net of tax of $(327) and $(98), respectively	(1,593)				(1,593)	(1,593)
Distributions to controlling interest	(1,021)						(1,021)
Stock-based compensation expense	18,684		18,684			18,684
Repurchase of common stock	(29,993)		(29,993)			(29,993)
Cash dividends declared and paid on common stock	(16,377)			(16,377)		(16,377)
Tax benefit/(deficiency) from the stock incentive plans
Common stock issued under employee stock plans	41,463		41,462			41,463		$ 1
Tax withholdings on vesting of restricted stock	(18,821)					(18,821)			$ (18,821)
Ending balance at Dec. 29, 2017	$ 2,055,924		$ 72,663	$ 1,985,064	$ (8,122)	$ 2,049,707	$ 6,217
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Outstanding		102