Revenue Recognition (Summary of Contract Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 27, 2024	Sep. 29, 2023
Revenue from Contract with Customer [Abstract]
Accounts receivable, net	$ 315,465	$ 262,245
Other non-current assets	120,609	94,674
Contract liabilities	31,644	31,505
Non-current contract liabilities	34,593	39,997
Other non-current liabilities	135,852	$ 108,339
Change ($)
Accounts receivable, net	53,220
Contract assets	15,348
Contract liabilities - current	139
Contract liabilities - non-current	$ (5,404)
Change (%)
Accounts receivable, net	20.00%
Contract assets	8.00%
Contract liabilities - current	0.00%
Contract liabilities - non-current	(14.00%)

Accounts Receivable, Net, Percent, Increase (Decrease)

No definition available.

Name:	dlb_AccountsReceivableNetPercentIncreaseDecrease
Namespace Prefix:	dlb_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Change In Contract With Customer, Assets And Liabilities Percent [Abstract]

+ References

No definition available.

+ Details

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

- Definition

Contract With Customer, Asset, Increase (Decrease)

+ References

No definition available.

+ Details

Name:	dlb_ContractWithCustomerAssetIncreaseDecrease
Namespace Prefix:	dlb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contract With Customer, Asset, Percent, Increase (Decrease)

+ References

No definition available.

+ Details

Name:	dlb_ContractWithCustomerAssetPercentIncreaseDecrease
Namespace Prefix:	dlb_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contract With Customer, Liability, Increase (Decrease), Current

+ References

No definition available.

+ Details

Name:	dlb_ContractWithCustomerLiabilityIncreaseDecreaseCurrent
Namespace Prefix:	dlb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Contract With Customer, Liability, Increase (Decrease), Noncurrent

+ References

No definition available.

+ Details

Name:	dlb_ContractWithCustomerLiabilityIncreaseDecreaseNoncurrent
Namespace Prefix:	dlb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Contract With Customer, Liability, Percent, Increase (Decrease), Current

+ References

No definition available.

+ Details

Name:	dlb_ContractWithCustomerLiabilityPercentIncreaseDecreaseCurrent
Namespace Prefix:	dlb_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contract With Customer, Liability, Percent, Increase (Decrease), Noncurrent

+ References

No definition available.

+ Details

Name:	dlb_ContractWithCustomerLiabilityPercentIncreaseDecreaseNoncurrent
Namespace Prefix:	dlb_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase (Decrease) In Accounts Receivable, Net

+ References

No definition available.

+ Details

Name:	dlb_IncreaseDecreaseInAccountsReceivableNet
Namespace Prefix:	dlb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481990/310-10-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481990/310-10-45-9

+ Details

Name:	us-gaap_AccountsReceivableNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_ChangeInContractWithCustomerAssetAndLiabilityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479837/606-10-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-8

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479837/606-10-45-2

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

+ References

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of noncurrent assets classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_OtherAssetsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.24)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_OtherLiabilitiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_RevenueFromContractWithCustomerAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration