Summary Of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 25, 2021	Jun. 26, 2020	Jun. 25, 2021	Jun. 26, 2020	Sep. 25, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 71,625		$ 71,625		$ 76,515
Total lease liabilities	76,609		76,609
Revenues	286,799	$ 246,909	996,231	$ 890,601
Gross margin	255,155	217,021	896,905	786,568
(Provision for)/benefit from income taxes	(4,565)	27,388	(37,859)	(580)
Net income (loss) attributable to Dolby Laboratories, Inc.	$ 54,621	$ 67,285	$ 266,036	$ 204,534
Diluted (in usd per share)	$ 0.52	$ 0.66	$ 2.54	$ 1.99
Accounts receivable, net	$ 275,080		$ 275,080		180,340
Contract assets, net of allowance for credit losses of $188 and $0	166,584		166,584		161,357
Prepaid expenses and other current assets	43,540		43,540		53,022
Other non-current assets	85,356		85,356		91,245
Accrued liabilities	255,033		255,033		219,974
Contract liabilities	18,201		18,201		15,436
Non-current contract liabilities	22,142		22,142		24,342
Other non-current liabilities	115,248		115,248		122,154
Retained earnings	2,626,447		2,626,447		$ 2,443,138
Net income	$ 54,560	$ 67,378	273,595	$ 204,643
Deferred income taxes			(26,479)	9,834
Accounts receivable, net			(93,848)	(64,247)
Contract assets			(5,402)	67,334
Prepaid expenses and other assets			15,468	(10,812)
Accounts payable and other liabilities			31,788	(46,851)
Contract liabilities			512	(2,222)
Net cash provided by operating activities			$ 337,980	$ 231,187