Commitments and Contingencies	3 Months Ended
Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Lease Obligations: We lease certain facilities and equipment under non-cancelable operating leases. Operating lease amounts exclude renewal option periods, property taxes, insurance, and maintenance expenses on leased properties. Our facility leases typically provide for rental adjustments for increases in base rent (up to specific limits), property taxes, insurance, and general property maintenance that would be recorded as rent expense. Rent expense was approximately $0.3 million for the three months ended December 31, 2018 and 2017. There are no off-balance sheet arrangements other than our operating leases. Asset Retirement Obligation: We have known conditional Asset Retirement Obligations (“AROs”) such as certain asset decommissioning and restoration of rented facilities to be performed in the future. Our ARO includes assumptions related to renewal option periods for those facilities where we expect to extend lease terms. The Company recognizes its estimate of the fair value of its ARO in the period incurred in long-term liabilities. The fair value of the ARO is also capitalized as property, plant and equipment. In future periods, the ARO is accreted for the change in its present value and capitalized costs are depreciated over the useful life of the related assets. If the fair value of the estimated ARO changes, an adjustment will be recorded to both the ARO and the asset retirement capitalized cost. Revisions in estimated liabilities can result from revisions of estimated inflation rates, changes in estimated retirement costs, and changes in the estimated timing of settling the ARO. The fair value of our ARO was estimated by discounting projected cash flows over the estimated life of the related assets using credit adjusted risk-free rates which ranged from 1.20% to 4.20%. There was no ARO settled during the three months ended December 31, 2018 and 2017. Accretion expense of $14,000 and $17,000 was recorded during the three months ended December 31, 2018 and 2017, respectively. EMCORE leases its primary facility in Alhambra, California covering six buildings where manufacturing, research and development, and general and administrative work is performed. In September 2017, a new lease for four of the six buildings was signed, which was effective on October 1, 2017. The new lease extends the terms of the lease for three years plus a three year option to extend the lease through September 2023. In connection with the lease agreement, the Company has recorded an ARO liability at December 31, 2018 and September 30, 2018 of $1.8 million. Leases related to the other two buildings expired in 2011, and these buildings are being occupied on a month-to-month basis. The Company’s ARO consists of legal requirements to return the existing leased facilities to their original state and certain environmental work to be performed due to the presence of a manufacturing fabrication operation and significant changes to the facilities over the past thirty years. In May 2016 (and retroactively effective on February 1, 2016) the Company entered into a five year lease agreement for facilities in Beijing, China where some manufacturing work is to be performed. In connection with the lease agreement, the Company has recorded an ARO liability in the amount of $0.1 million at December 31, 2018 and September 30, 2018. Indemnifications: We have agreed to indemnify certain customers against claims of infringement of intellectual property rights of others in our sales contracts with these customers. Historically, we have not paid any claims under these indemnification obligations. Legal Proceedings: We are subject to various legal proceedings, claims, and litigation, either asserted or unasserted, that arise in the ordinary course of business. The outcome of these matters is currently not determinable and we are unable to estimate a range of loss, should a loss occur, from these proceedings. The ultimate outcome of legal proceedings involves judgments, estimates and inherent uncertainties and the results of these matters cannot be predicted with certainty. Professional legal fees are expensed when incurred. We accrue for contingent losses when such losses are probable and reasonably estimable. In the event that estimates or assumptions prove to differ from actual results, adjustments are made in subsequent periods to reflect more current information. Should we fail to prevail in any legal matter or should several legal matters be resolved against the Company in the same reporting period, then the financial results of that particular reporting period could be materially affected. a) Intellectual Property Lawsuits We protect our proprietary technology by applying for patents where appropriate and, in other cases, by preserving the technology, related know-how and information as trade secrets. The success and competitive position of our product lines are impacted by our ability to obtain intellectual property protection for our research and development efforts. We have, from time to time, exchanged correspondence with third parties regarding the assertion of patent or other intellectual property rights in connection with certain of our products and processes. b) Phoenix Navigation Components, LLC Legal Proceedings On June 12, 2018, Phoenix Navigation Components, LLC (“Phoenix”) commenced an arbitration against EMCORE with the American Arbitration Association (“AAA”) in New York. On August 31, 2018, Phoenix filed a First Amended Demand for Arbitration, asserting the following claims: breach of contract, breach of the covenant of good faith and fair dealing, misappropriation of trade secrets (under the Defend Trade Secrets Act, 18 U.S.C. § 1836, and New York law), conversion, unjust enrichment, correction of inventorship relating to U.S. Patent No. 8,773,665, and declaratory relief, relating to EMCORE’s termination of certain agreements entered into between EMCORE and Phoenix related to the purported license of certain intellectual property related to fiber optic gyroscope technology and disputed royalty payments related thereto. On September 14, 2018, EMCORE filed an Answering Statement and Counterclaim, denying all of Phoenix’s claims and asserting counterclaims for breach of the implied covenant of good faith and fair dealing and declaratory relief. An arbitration hearing on all claims with the exception of the patent claims was held on January 8 through 12, 2019, and closing arguments are currently scheduled for March 29, 2019. A second arbitration hearing on the patent claims has been set for July 29, 2019. We believe that the claims asserted by Phoenix are without merit and we intend to vigorously defend ourselves against them. On June 21, 2018, Phoenix Navigation Components, LLC commenced a special proceeding against EMCORE in the New York Supreme Court, Commercial Division, Index No. 653128/2018. As part of the special proceeding, Phoenix filed an application for a preliminary injunction in aid of arbitration pursuant to CLPR 7502(c), in connection with the AAA arbitration proceeding in New York. On August 6, 2018, Phoenix’s application was resolved pursuant to a stipulation between EMCORE and Phoenix. This special proceeding remains open pending resolution of the AAA arbitration. On September 18, 2018, EMCORE filed a complaint against Phoenix in the United States District Court for the Central District of California seeking a declaratory judgment with respect to U.S. Patent No. 8,773,665. On October 19, 2018, Phoenix filed a Motion to Stay Pending Arbitration or to Dismiss the Complaint. On December 7, 2018, the United States District Court for the Central District of California issued an order granting Phoenix's motion to dismiss this action.

Commitments and Contingencies

Operating Lease Obligations: We lease certain facilities and equipment under non-cancelable operating leases. Operating lease amounts exclude renewal option periods, property taxes, insurance, and maintenance expenses on leased properties. Our facility leases typically provide for rental adjustments for increases in base rent (up to specific limits), property taxes, insurance, and general property maintenance that would be recorded as rent expense. Rent expense was approximately $0.3 million for the three months ended December 31, 2018 and 2017. There are no off-balance sheet arrangements other than our operating leases.

Asset Retirement Obligation: We have known conditional Asset Retirement Obligations (“AROs”) such as certain asset decommissioning and restoration of rented facilities to be performed in the future. Our ARO includes assumptions related to renewal option periods for those facilities where we expect to extend lease terms. The Company recognizes its estimate of the fair value of its ARO in the period incurred in long-term liabilities. The fair value of the ARO is also capitalized as property, plant and equipment.

In future periods, the ARO is accreted for the change in its present value and capitalized costs are depreciated over the useful life of the related assets. If the fair value of the estimated ARO changes, an adjustment will be recorded to both the ARO and the asset retirement capitalized cost. Revisions in estimated liabilities can result from revisions of estimated inflation rates, changes in estimated retirement costs, and changes in the estimated timing of settling the ARO. The fair value of our ARO was estimated by discounting projected cash flows over the estimated life of the related assets using credit adjusted risk-free rates which ranged from 1.20% to 4.20%. There was no ARO settled during the three months ended December 31, 2018 and 2017. Accretion expense of $14,000 and $17,000 was recorded during the three months ended December 31, 2018 and 2017, respectively.

EMCORE leases its primary facility in Alhambra, California covering six buildings where manufacturing, research and development, and general and administrative work is performed. In September 2017, a new lease for four of the six buildings was signed, which was effective on October 1, 2017. The new lease extends the terms of the lease for three years plus a three year option to extend the lease through September 2023. In connection with the lease agreement, the Company has recorded an ARO liability at December 31, 2018 and September 30, 2018 of $1.8 million. Leases related to the other two buildings expired in 2011, and these buildings are being occupied on a month-to-month basis.

The Company’s ARO consists of legal requirements to return the existing leased facilities to their original state and certain environmental work to be performed due to the presence of a manufacturing fabrication operation and significant changes to the facilities over the past thirty years.

In May 2016 (and retroactively effective on February 1, 2016) the Company entered into a five year lease agreement for facilities in Beijing, China where some manufacturing work is to be performed. In connection with the lease agreement, the Company has recorded an ARO liability in the amount of $0.1 million at December 31, 2018 and September 30, 2018.

Indemnifications: We have agreed to indemnify certain customers against claims of infringement of intellectual property rights of others in our sales contracts with these customers. Historically, we have not paid any claims under these indemnification obligations.

Legal Proceedings: We are subject to various legal proceedings, claims, and litigation, either asserted or unasserted, that arise in the ordinary course of business. The outcome of these matters is currently not determinable and we are unable to estimate a range of loss, should a loss occur, from these proceedings. The ultimate outcome of legal proceedings involves judgments, estimates and inherent uncertainties and the results of these matters cannot be predicted with certainty. Professional legal fees are expensed when incurred. We accrue for contingent losses when such losses are probable and reasonably estimable. In the event that estimates or assumptions prove to differ from actual results, adjustments are made in subsequent periods to reflect more current information. Should we fail to prevail in any legal matter or should several legal matters be resolved against the Company in the same reporting period, then the financial results of that particular reporting period could be materially affected.

a) Intellectual Property Lawsuits

We protect our proprietary technology by applying for patents where appropriate and, in other cases, by preserving the technology, related know-how and information as trade secrets. The success and competitive position of our product lines are impacted by our ability to obtain intellectual property protection for our research and development efforts. We have, from time to time, exchanged correspondence with third parties regarding the assertion of patent or other intellectual property rights in connection with certain of our products and processes.

b) Phoenix Navigation Components, LLC Legal Proceedings

On June 12, 2018, Phoenix Navigation Components, LLC (“Phoenix”) commenced an arbitration against EMCORE with the American Arbitration Association (“AAA”) in New York. On August 31, 2018, Phoenix filed a First Amended Demand for Arbitration, asserting the following claims: breach of contract, breach of the covenant of good faith and fair dealing, misappropriation of trade secrets (under the Defend Trade Secrets Act, 18 U.S.C. § 1836, and New York law), conversion, unjust enrichment, correction of inventorship relating to U.S. Patent No. 8,773,665, and declaratory relief, relating to EMCORE’s termination of certain agreements entered into between EMCORE and Phoenix related to the purported license of certain intellectual property related to fiber optic gyroscope technology and disputed royalty payments related thereto. On September 14, 2018, EMCORE filed an Answering Statement and Counterclaim, denying all of Phoenix’s claims and asserting counterclaims for breach of the implied covenant of good faith and fair dealing and declaratory relief. An arbitration hearing on all claims with the exception of the patent claims was held on January 8 through 12, 2019, and closing arguments are currently scheduled for March 29, 2019. A second arbitration hearing on the patent claims has been set for July 29, 2019. We believe that the claims asserted by Phoenix are without merit and we intend to vigorously defend ourselves against them.

On June 21, 2018, Phoenix Navigation Components, LLC commenced a special proceeding against EMCORE in the New York Supreme Court, Commercial Division, Index No. 653128/2018. As part of the special proceeding, Phoenix filed an application for a preliminary injunction in aid of arbitration pursuant to CLPR 7502(c), in connection with the AAA arbitration proceeding in New York. On August 6, 2018, Phoenix’s application was resolved pursuant to a stipulation between EMCORE and Phoenix. This special proceeding remains open pending resolution of the AAA arbitration.

On September 18, 2018, EMCORE filed a complaint against Phoenix in the United States District Court for the Central District of California seeking a declaratory judgment with respect to U.S. Patent No. 8,773,665. On October 19, 2018, Phoenix filed a Motion to Stay Pending Arbitration or to Dismiss the Complaint. On December 7, 2018, the United States District Court for the Central District of California issued an order granting Phoenix's motion to dismiss this action.