Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Weighted Average Grant Date Fair Value Intrinsic Value Of Exercises And Fair Value Of Options Vested [Table Text Block]

No definition available.

Name:	dlb_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageGrantDateFairValueIntrinsicValueOfExercisesAndFairValueOfOptionsVestedTableTextBlock
Namespace Prefix:	dlb_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Schedule of Share-Based Payment Fair Value by Vesting Date [Table Text Block]

No definition available.

Name:	dlb_ScheduleofShareBasedPaymentFairValuebyVestingDateTableTextBlock
Namespace Prefix:	dlb_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Schedule of Stock Repurchase Activity [Table Text Block]

No definition available.

Name:	dlb_ScheduleofStockRepurchaseActivityTableTextBlock
Namespace Prefix:	dlb_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Schedule of Tax Benefit from Exercise of Options [Table Text Block]

No definition available.

Name:	dlb_ScheduleofTaxBenefitfromExerciseofOptionsTableTextBlock
Namespace Prefix:	dlb_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Schedule of Treasury Stock Authorizations [Table Text Block]

No definition available.

Name:	dlb_ScheduleofTreasuryStockAuthorizationsTableTextBlock
Namespace Prefix:	dlb_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Stockholders Equity And Stock-Based Compensation Abstract

No definition available.

Name:	dlb_StockholdersEquityAndStockBasedCompensationAbstract
Namespace Prefix:	dlb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of share-based payment arrangement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Name:	us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of information related to dividends declared, including paid and unpaid dividends.

No definition available.

Name:	us-gaap_DividendsDeclaredTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of cost recognized for award under share-based payment arrangement by plan. Includes, but is not limited to, related tax benefit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Name:	us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement.

Name:	us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 718
-SubTopic 10
-Subparagraph (f)(2)
-Name Accounting Standards Codification
-Paragraph 2
-Section 50
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Name:	us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2