Legal Proceedings	12 Months Ended
Sep. 30, 2011
Legal Proceedings [Abstract]
Legal Proceedings	12. Legal Proceedings In March 1997, an unrelated third party filed a lawsuit against us alleging breach of a written agreement. In April 2002, we settled the dispute and agreed to pay a total of $30.0 million, without interest, in ten equal annual installments of $3.0 million per year beginning in June 2002. We recorded this liability at its present value of $24.2 million on the consolidated balance sheet. Interest related to this liability is recorded quarterly and is included in interest expense on the accompanying consolidated statements of operations. Other than such payments, neither party has any material obligations as a result of the settlement. As of September 30, 2011, we had paid all amounts due under this settlement. During the fiscal quarter ended July 1, 2011, we filed patent infringement lawsuits in the U.S. and in Germany against Research in Motion Ltd. ("RIM"), a previously unlicensed user of certain of our patented technologies. In July 2011, RIM signed a license agreement with Via Licensing Corporation ("Via"), our wholly-owned subsidiary and the licensing administrator for the patent pool which includes Dolby's essential AAC patents, which entitled us to back royalties for Dolby technologies used in RIM's products. Based on this license agreement, we recognized revenue of $15.2 million during the fourth quarter of fiscal 2011 for back royalties related to the Dolby patents and Via administration fees, including $11.3 million attributable to periods prior to fiscal 2011. We also received interest related to these back royalties of $2.2 million, which was recognized as interest income. We are involved in various legal proceedings from time to time arising from the normal course of business activities, including claims of alleged infringement of intellectual property rights, commercial, employment, and other matters. In our opinion, resolution of these pending matters is not expected to have a material adverse impact on our operating results or financial condition. Given the unpredictable nature of legal proceedings, it is possible that an unfavorable resolution of one or more such proceedings could materially affect our future operating results or financial condition in a particular period; however, based on the information known by us as of the date of this filing and the rules and regulations applicable to the preparation of our financial statements, any such amount is either immaterial or it is not possible to provide an estimated amount of any such potential loss.

Legal Proceedings

12 Months Ended

Sep. 30, 2011

12. Legal Proceedings

In March 1997, an unrelated third party filed a lawsuit against us alleging breach of a written agreement. In April 2002, we settled the dispute and agreed to pay a total of $30.0 million, without interest, in ten equal annual installments of $3.0 million per year beginning in June 2002. We recorded this liability at its present value of $24.2 million on the consolidated balance sheet. Interest related to this liability is recorded quarterly and is included in interest expense on the accompanying consolidated statements of operations. Other than such payments, neither party has any material obligations as a result of the settlement. As of September 30, 2011, we had paid all amounts due under this settlement.

During the fiscal quarter ended July 1, 2011, we filed patent infringement lawsuits in the U.S. and in Germany against Research in Motion Ltd. ("RIM"), a previously unlicensed user of certain of our patented technologies. In July 2011, RIM signed a license agreement with Via Licensing Corporation ("Via"), our wholly-owned subsidiary and the licensing administrator for the patent pool which includes Dolby's essential AAC patents, which entitled us to back royalties for Dolby technologies used in RIM's products. Based on this license agreement, we recognized revenue of $15.2 million during the fourth quarter of fiscal 2011 for back royalties related to the Dolby patents and Via administration fees, including $11.3 million attributable to periods prior to fiscal 2011. We also received interest related to these back royalties of $2.2 million, which was recognized as interest income.

We are involved in various legal proceedings from time to time arising from the normal course of business activities, including claims of alleged infringement of intellectual property rights, commercial, employment, and other matters. In our opinion, resolution of these pending matters is not expected to have a material adverse impact on our operating results or financial condition. Given the unpredictable nature of legal proceedings, it is possible that an unfavorable resolution of one or more such proceedings could materially affect our future operating results or financial condition in a particular period; however, based on the information known by us as of the date of this filing and the rules and regulations applicable to the preparation of our financial statements, any such amount is either immaterial or it is not possible to provide an estimated amount of any such potential loss.