Summary Of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 25, 2020	Dec. 27, 2019	Sep. 25, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 75,460		$ 76,515
Total lease liabilities	80,073
Revenues	389,874	$ 291,877
Gross margin	354,570	254,562
Provision for income taxes	(24,272)	(5,863)
Net income (loss) attributable to Dolby Laboratories, Inc.	$ 135,198	$ 48,753
Diluted (in usd per share)	$ 1.30	$ 0.47
Accounts receivable, net	$ 293,948		180,340
Contract assets, net of allowance for credit losses of $215 and $0	187,539		161,357
Prepaid expenses and other current assets	51,390		53,022
Other non-current assets	86,825		91,245
Accrued liabilities	250,253		219,974
Contract liabilities	21,202		15,436
Non-current contract liabilities	23,766		24,342
Other non-current liabilities	121,196		122,154
Retained earnings	2,565,670		$ 2,443,138
Net income	142,690	$ 48,591
Deferred income taxes	(15,439)	(9,174)
Accounts receivable, net	(111,902)	(2,331)
Contract assets	(26,384)	(9,310)
Prepaid expenses and other assets	6,397	(13,245)
Accounts payable and other liabilities	22,272	(30,785)
Contract liabilities	5,153	(724)
Net cash provided by operating activities	$ 82,160	$ 31,159