Summary Of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018	Sep. 28, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 302,159	$ 214,780	$ 942,793	$ 814,029
Gross margin	262,469	180,397	827,899	717,726
Provision for income taxes	(2,163)	9,067	(14,486)	(163,070)
Net income (loss) attributable to Dolby Laboratories, Inc.	$ 39,574	$ 3,116	$ 211,233	$ 15,030
Diluted (in usd per share)	$ 0.38	$ 0.03	$ 2.01	$ 0.14
Accounts receivable, net	$ 231,185		$ 231,185		$ 166,133
Contract assets	182,912		182,912		165,959
Prepaid expenses and other current assets	41,030		41,030		34,890
Deferred taxes	109,208		109,208		74,766
Other non-current assets	100,550		100,550		80,080
Accrued liabilities	243,738		243,738		243,128
Contract liabilities	19,435		19,435		17,468
Non-current contract liabilities	24,428		24,428		25,887
Other non-current liabilities	186,765		186,765		183,799
Retained earnings	2,328,918		2,328,918		2,313,539
Net income	$ 39,637	$ 3,259	211,570	$ 15,451
Deferred income taxes			(34,872)	15,163
Accounts receivable			(70,022)	1,975
Contract assets			(16,942)	12,897
Prepaid expenses and other assets			(13,719)	(13,718)
Accounts payable and other liabilities			(10,733)	(16,368)
Contract liabilities			491	(838)
Net cash provided by operating activities			$ 197,194	240,471
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		317,447		906,599
Gross margin		282,982		810,299
Provision for income taxes		13,302		198,332
Net income (loss) attributable to Dolby Laboratories, Inc.		$ 83,145		$ 72,154
Diluted (in usd per share)		$ 0.78		$ 0.67
Accounts receivable, net					137,151
Contract assets					0
Prepaid expenses and other current assets					35,209
Deferred taxes					101,070
Other non-current assets					42,280
Accrued liabilities					223,594
Contract liabilities					23,931
Non-current contract liabilities					40,064
Other non-current liabilities					150,960
Retained earnings					2,139,154
Net income				$ 72,575
Deferred income taxes				47,145
Accounts receivable				(78,480)
Contract assets				0
Prepaid expenses and other assets				(13,719)
Accounts payable and other liabilities				(12,781)
Contract liabilities				(366)
Net cash provided by operating activities				240,471
Restatement Adjustment | Effect of Adopting ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		$ (102,667)		(92,570)
Gross margin		(102,585)		(92,573)
Provision for income taxes		(22,369)		(35,262)
Net income (loss) attributable to Dolby Laboratories, Inc.		$ (80,029)		$ (57,124)
Diluted (in usd per share)		$ (0.75)		$ (0.53)
Accounts receivable, net					28,982
Contract assets					165,959
Prepaid expenses and other current assets					(319)
Deferred taxes					(26,304)
Other non-current assets					37,800
Accrued liabilities					19,534
Contract liabilities					(6,463)
Non-current contract liabilities					(14,177)
Other non-current liabilities					32,839
Retained earnings					$ 174,385
Net income				$ (57,124)
Deferred income taxes				(31,982)
Accounts receivable				80,455
Contract assets				12,897
Prepaid expenses and other assets				1
Accounts payable and other liabilities				(3,587)
Contract liabilities				(472)
Net cash provided by operating activities				$ 0