Interim Condensed Consolidated Statements Of Stockholders' Equity - USD ($) $ 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		101,000
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	104,301			103,964		103,964	337
Translation adjustments, net of tax of $829 and $(64), respectively	(3,279)				(3,073)	(3,073)	(206)
Unrealized gains (losses) on available-for-sale securities, net of tax of $(327) and $(98), respectively	(1,438)				(1,438)	(1,438)
Distributions to controlling interest	(2,094)						(2,094)
Stock-based compensation expense	33,198		33,198			33,198
Shares repurchased (in shares)								(1,000)
Repurchase of common stock	(50,000)		(49,999)			(50,000)
Cash dividends declared and paid on common stock	(28,494)			(28,494)		(28,494)
Tax benefit/(deficiency) from the stock incentive plans	3,818		3,818			3,818
Common stock issued under employee stock plans	24,210		24,208			24,210		$ 2
Tax withholdings on vesting of restricted stock	(15,799)					(15,799)		$ (1)	$ (15,798)
Ending balance at Mar. 31, 2017	2,043,158		37,459	2,013,790	(14,708)	2,036,642	6,516
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Outstanding		101,000
Shares, Outstanding		101,000
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	(10,713)			(10,991)		(10,991)	278
Translation adjustments, net of tax of $829 and $(64), respectively	5,482				5,289	5,289	193
Unrealized gains (losses) on available-for-sale securities, net of tax of $(327) and $(98), respectively	(3,152)				(3,152)	(3,152)
Distributions to controlling interest	(1,022)
Stock-based compensation expense	$ 36,375		36,375			36,375
Shares repurchased (in shares)	(571,589)							(1,000)
Repurchase of common stock	$ (34,993)		(34,992)			(34,993)
Cash dividends declared and paid on common stock	(32,956)			(32,956)		(32,956)
Tax benefit/(deficiency) from the stock incentive plans
Common stock issued under employee stock plans	71,061		71,059			71,061		$ 2
Tax withholdings on vesting of restricted stock	(19,946)					(19,946)			$ (19,946)
Ending balance at Mar. 30, 2018	$ 2,153,978		$ 113,827	$ 2,039,116	$ (5,616)	$ 2,147,429	$ 6,549
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Outstanding		102,000