Nature of Operations	12 Months Ended
Nature of Operations	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations Anterix Inc. (the “Company”) is a wireless communications company focused on commercializing its spectrum assets to enable its targeted utility and critical infrastructure customers to deploy private broadband networks and on offering innovative broadband solutions to the same target customers. The Company is the largest holder of licensed spectrum in the 900 MHz band (896 - 901 / 935 - 940 MHz) with nationwide coverage throughout the contiguous United States, Hawaii, Alaska and Puerto Rico. On May 13, 2020, the FCC approved the Report and Order (the “Report and Order”) to modernize and realign the 900 MHz band to increase its usability and capacity by allowing it to be utilized for the deployment of broadband networks, technologies and solutions. The Report and Order was published in the Federal Register on July 16, 2020, and became effective on August 17, 2020. The Company is now engaged in qualifying for and securing broadband licenses from the FCC. At the same time, the Company is pursuing opportunities to monetize the broadband spectrum it secures to its targeted utility and critical infrastructure customers. The Company was originally incorporated in California in 1997 and reincorporated in Delaware in 2014. In November 2015, the Company changed its name from Pacific DataVision, Inc. to pdvWireless, Inc. In August 2019, the Company changed its name from pdvWireless, Inc. to Anterix Inc. The Company maintains offices in Woodland Park, New Jersey, McLean, Virginia and Abilene, Texas. Business Developments On October 28, 2022, the Company entered into an agreement with Xcel Energy Services Inc. (“Xcel Energy”) providing Xcel Energy dedicated long-term usage of the Company’s 900 MHz Broadband Spectrum for a term of 20 years throughout Xcel Energy’s service territory in eight states (the “Xcel Energy Agreement”). The Xcel Energy Agreement also provides Xcel Energy an option to extend the agreement for two 10-year terms for additional payments. The Xcel Energy Agreement allows Xcel Energy to deploy a PLTE network to support its grid modernization initiatives for the benefit of its approximately 3.7 million electricity customers and 2.1 million natural gas customers. The scheduled prepayments for the 20-year initial term of the Xcel Energy Agreement total $80.0 million, of which $8.0 million was received by the Company in December 2022. See Note 3 Revenue for further discussion on the Xcel Energy Agreement. In September 2021, the Company entered into a long-term lease agreement of 900 MHz Broadband Spectrum with Evergy, Inc. (“Evergy”), (the “Evergy Agreement”). The Evergy service territories covered by the Evergy Agreement are in Kansas and Missouri with a population of approximately 3.9 million people. The Evergy Agreement is for an initial term of 20 years with two 10-year renewal options for additional payments. The Company received full prepayment of $30.2 million for the initial 20-year term in October 2021. During the year ended March 31, 2023, the Company delivered to Evergy the 1.4 x 1.4 cleared 900 MHz Broadband Spectrum and the associated broadband licenses for 81 counties. The revenue recognized for the year ended March 31, 2023 was approximately $0.6 million. See Note 3 Revenue for further discussion on the Evergy Agreement. In February 2021, the Company entered into an agreement with San Diego Gas & Electric Company, a subsidiary of Sempra Energy (“SDG&E”), to provide 900 MHz Broadband Spectrum throughout SDG&E’s California service territory, including San Diego and Imperial Counties and portions of Orange County for a total payment of $50.0 million. 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 associated broadband licenses to SDG&E and the relevant cleared 900 MHz Broadband Spectrum. 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. See Note 12 Contingencies for further discussion. In May 2022, the Company issued Motorola Solutions, Inc. (“Motorola”) 500,000 shares of its common stock (the “Shares”). Motorola received the Shares by electing to convert 500,000 Class B Units (the “Units”) it held in the Company’s subsidiary, PDV Spectrum Holding Company, LLC (the “Subsidiary”). Motorola acquired the Units in September 2014 in connection with a Spectrum Lease Agreement between Motorola and the Subsidiary (the “2014 Motorola Spectrum Agreement”). Under the 2014 Motorola Spectrum Agreement, Motorola leased a portion of our narrowband spectrum, which was held by the Subsidiary, in consideration for an upfront, fully-paid leasing fee of $7.5 million and a $10.0 million investment in the Units. Motorola had the right at any time to convert its Units into the Shares, representing a conversion price of $20.00 per share.