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	180,487			180,007		180,007	480
Translation adjustments, net of tax of $829 and $(64), respectively	(12)				42	42	(54)
Unrealized gains (losses) on available-for-sale securities, net of tax of $(327) and $(98), respectively	(1,363)				(1,363)	(1,363)
Distributions to controlling interest	(2,094)						(2,094)
Stock-based compensation expense	48,940		48,940			48,940
Shares repurchased (in shares)								(2,000)
Repurchase of common stock	(74,994)		(74,992)			(74,994)
Cash dividends declared and paid on common stock	(42,768)			(42,768)		(42,768)
Tax benefit/(deficiency) from the stock incentive plans	4,558		4,558			4,558
Common stock issued under employee stock plans	47,765		47,763			47,765		$ 2
Tax withholdings on vesting of restricted stock	(16,875)					(16,875)			$ (16,875)
Ending balance at Jun. 30, 2017	2,122,379		51,426	2,075,559	(11,518)	2,115,568	6,811
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	72,575			72,154		72,154	421
Translation adjustments, net of tax of $829 and $(64), respectively	(2,815)				(2,735)	(2,735)	(80)
Unrealized gains (losses) on available-for-sale securities, net of tax of $(327) and $(98), respectively	(2,813)				(2,813)	(2,813)
Distributions to controlling interest	(1,022)						(1,022)
Stock-based compensation expense	$ 53,476		53,476			53,476
Shares repurchased (in shares)	(1,468,278)							(1,000)
Repurchase of common stock	$ (90,480)		(90,479)			(90,480)
Cash dividends declared and paid on common stock	(49,596)			(49,596)		(49,596)
Tax benefit/(deficiency) from the stock incentive plans
Common stock issued under employee stock plans	85,941		85,938			85,941		$ 3
Tax withholdings on vesting of restricted stock	(21,189)					(21,189)			$ (21,189)
Ending balance at Jun. 29, 2018	$ 2,187,919		$ 89,077	$ 2,105,621	$ (13,301)	$ 2,181,500	$ 6,419
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Outstanding		103,000