Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 25, 2015	Sep. 26, 2014	Sep. 27, 2013	Jun. 26, 2015
Summary Of Significant Accounting Policies [Line Items]
Maximum credit exposure (percent)	5.00%
Goodwill	$ 307,708	$ 277,574	$ 279,724
Advertising expense	46,202	37,895	32,834
Transaction and re-measurement gains/losses	$ (142)	498	$ 73
Dolby Entertainment Technology [Member]
Summary Of Significant Accounting Policies [Line Items]
Goodwill				$ 312,500
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets with definite lives, useful life, minimum years	3 years
Minimum [Member] | Internal Use Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets with definite lives, useful life, minimum years	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets with definite lives, useful life, minimum years	17 years
Corrective royalties, percentage of license revenue (percent)	1.00%
Maximum [Member] | Internal Use Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible assets with definite lives, useful life, minimum years	5 years
Foreign Exchange Forward [Member]
Summary Of Significant Accounting Policies [Line Items]
Notional amount of derivative	$ 22,300	$ 22,900
Customer Concentration Risk [Member] | Sales Revenue, Goods, Net [Member]
Summary Of Significant Accounting Policies [Line Items]
Percent of revenue from significant customer (percent)	12.00%	11.00%	12.00%