v2.3.0.15

Legal Proceedings (Details) (USD $) In Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2011
Legal Proceedings [Line Items]
Amount agreed to pay on settlement of dispute		$ 30.0
Annual installments		3.0
Present value of contingency liability	24.2	24.2
Back royalties recognized as revenue	15.2
Amount received as interest related to back royalties	2.2
Royalties Prior to Fiscal 2011 [Member]
Legal Proceedings [Line Items]
Back royalties recognized as revenue	$ 11.3

X

- Definition

Amount Received As Interest Related To These Back Royalties Recognized As Interest Income

+ Details

Name:	dlb_AmountReceivedAsInterestRelatedToTheseBackRoyaltiesRecognizedAsInterestIncome
Namespace Prefix:	dlb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Legal Proceedings [Line Items]

+ Details

Name:	dlb_LegalProceedingsLineItems
Namespace Prefix:	dlb
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Loss contingency settlements periodic payments.

+ Details

Name:	dlb_LossContingencySettlementsPeriodicPayments
Namespace Prefix:	dlb
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

This element represents the gross amount awarded, to be received by, or to be remitted to the entity in settlement of litigation occurring during the period.

+ Details

Name:	us-gaap_LitigationSettlementGross
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The carrying amount as of the balance sheet date of the combined total of loss contingency liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

+ Details

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Cash received for royalties during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 27

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3536-108585

+ Details

Name:	us-gaap_ProceedsFromRoyaltiesReceived
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration