Summary Of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 27, 2020	Mar. 29, 2019	Mar. 27, 2020	Mar. 29, 2019	Sep. 28, 2019	Sep. 27, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 79,439		$ 79,439		$ 62,100	$ 0
Total lease liabilities	81,836		81,836		$ 64,600
Revenues	351,815	$ 338,258	643,692	$ 640,634
Gross margin	314,985	301,683	569,547	565,430
Provision for income taxes	(22,105)	(36,427)	(27,968)	(12,323)
Net income (loss) attributable to Dolby Laboratories, Inc.	$ 88,496	$ 73,440	$ 137,249	$ 171,659
Diluted (in usd per share)	$ 0.86	$ 0.70	$ 1.33	$ 1.63
Accounts receivable, net	$ 247,043		$ 247,043			189,115
Contract assets	223,739		223,739			195,651
Prepaid expenses and other current assets	51,156		51,156			39,704
Other non-current assets	97,353		97,353			93,395
Accrued liabilities	245,869		245,869			268,144
Contract liabilities	19,745		19,745			19,991
Non-current contract liabilities	25,074		25,074			24,404
Other non-current liabilities	178,805		178,805			177,462
Retained earnings	2,395,575		2,395,575			$ 2,327,877
Net income	$ 88,674	$ 73,575	137,265	$ 171,933
Deferred income taxes			(15,141)	(38,548)
Accounts receivable			(60,870)	(14,221)
Contract assets			(28,086)	(78,949)
Prepaid expenses and other assets			(16,068)	(15,273)
Accounts payable and other liabilities			(22,033)	(14,190)
Contract liabilities			452	1,061
Net cash provided by operating activities			$ 96,899	$ 105,844