Contingencies	12 Months Ended
Contingencies	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Contingent Liability In February 2021, the Company entered into an agreement with SDG&E to sell 900 MHz Broadband Spectrum throughout SDG&E’s California service territory, including San Diego and Imperial Counties and portions of Orange County (the “SDG&E Agreement”), for a total payment of $50.0 million. The SDG&E Agreement will support SDG&E’s deployment of a PLTE network for its California service territory, with a population of approximately 3.6 million people. Delivery of the relevant 900 MHz Broadband Spectrum and the associated broadband licenses by county to SDG&E commenced in Fiscal 2023 and is scheduled for completion before the end of fiscal year 2024. The total payment of $50.0 million is comprised of an initial payment of $20.0 million, received in February 2021, and the remaining $30.0 million payment, which is due through fiscal year 2024 as the Company delivers the relevant cleared 900 MHz Broadband Spectrum and the associated broadband licenses to SDG&E. In September 2022, the Company delivered to SDG&E 1.4 x 1.4 cleared 900 MHz Broadband Spectrum and the associated broadband license related to Imperial County and received a milestone payment of $0.2 million. A gain or loss on the sale of spectrum will be recognized for each county once the Company delivers the cleared 900 MHz Broadband Spectrum and the associated broadband licenses to SDG&E in full. As the Company is required to refund payments it has received in the event of termination or non-delivery of the specific county’s 900 MHz Broadband Spectrum, it recorded the $20.2 million received from SDG&E as contingent liability in the Company’s Consolidated Balance Sheet. As of March 31, 2023, the Company recorded the $20.2 million payments from SDG&E as a short-term liability due to the expected timing of delivery. Xcel Energy Guaranty In connection with Xcel Energy Agreement, the Company entered into a guaranty agreement, under which the Company guaranteed the delivery of the relevant 900 MHz Broadband Spectrum and the associated broadband licenses in Xcel Energy’s service territory in eight states along with other commercial obligations. In the event of default or non-delivery of the specific territory’s 900 MHz Broadband Spectrum, the Company is required to refund payments it has received. In addition, to the extent Anterix has performed any obligations, the Company’s liability and remaining obligations under the Xcel Energy Agreement will extend only to the remaining unperformed obligations. The Company recorded $8.0 million in deferred revenue in connection with the prepayment received as delivery of the relevant cleared 900 MHz Broadband licenses or counties is expected to commence in the first quarter of Fiscal 2024 through 2029. As of March 31, 2023, the maximum potential liability of future undiscounted payments under this agreement is approximately $8.0 million. Litigation In addition to commitments and obligations in the ordinary course of business as reflected in the lease footnote above, the Company may be subject, from time to time, to various claims and pending and potential legal actions arising out of the normal conduct of its business. The Company assesses contingencies to determine the degree of probability and range of possible loss for potential accrual in its financial statements. Because litigation is inherently unpredictable and unfavorable resolutions could occur, assessing litigation contingencies is highly subjective and requires judgments about future events. When evaluating contingencies, the Company may be unable to provide a meaningful estimate due to a number of factors, including the procedural status of the matter in question, the presence of complex or novel legal theories and/or the ongoing discovery and development of information important to the matters. In addition, damage amounts claimed in litigation against it may be unsupported, exaggerated or unrelated to possible outcomes, and as such are not meaningful indicators of its potential liability. The Company regularly reviews contingencies to determine the adequacy of its accruals and related disclosures. During the period presented, the Company has not recorded any accrual for loss contingencies associated with any claims or legal proceedings; determined that an unfavorable outcome is probable or reasonably possible; or determined that the amount or range of any possible loss is reasonably estimable. However, the outcome of legal proceedings and claims brought against the Company is subject to significant uncertainty. Therefore, although management considers the likelihood of a material adverse outcome to be remote, if one or more of these legal matters were resolved against the Company in a reporting period, the Company’s consolidated financial statements for that reporting period could be materially adversely affected. Pandemic and Macroeconomic Conditions In December 2020, the Company deferred payroll taxes under the Coronavirus Aid Relief and Economic Security Act, which was signed into law on March 27, 2020. The deferral amounted to approximately $0.3 million, which has assisted the Company in managing the financial impact caused by the pandemic. Of the total deferred, approximately $0.2 million was remitted to the IRS during Fiscal 2022, with the remaining amount remitted to the IRS during Fiscal 2023. Recent macroeconomic events, including the outbreak of COVID-19, inflation, and geopolitical matters, have increased operating costs and could increase production costs or result in delays in customer contracting or the availability of equipment necessary for the deployment of our target customers’ planned PLTE projects. The Company continues to closely monitor these risks. Although difficult to quantify, the Company believes the current macroeconomic environment, including inflation, may have an adverse effect on the Company’s target customers’ businesses, which may harm the Company’s commercialization efforts and negatively impact the Company’s revenues. If the Company is not able to control its higher operating costs or if the Company’s commercialization efforts are slowed or negatively impacted, continued periods of high inflation could have a material adverse effect on the Company’s business, operating results and financial condition.