Nature of Operations	12 Months Ended
Nature of Operations	Mar. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations Anterix Inc. (the “Company”) is the utility industry’s partner, empowering enhanced visibility, control and security for a modern grid. The Company’s vision is to deliver secure, scalable solutions enabled by private wireless broadband connectivity, for the benefit of utilities and the communities that they serve. As the largest holder of licensed spectrum in the 900 MHz band (896-901/935-940 MHz) throughout the contiguous United States, plus Hawaii, Alaska and Puerto Rico, the Company is uniquely positioned to deliver solutions that support secure, resilient and customer-controlled operations. The Company is focused on commercializing its spectrum assets and expanding the benefits and solutions it offers to enable the Company’s targeted utility and critical infrastructure customers to deploy private broadband networks. 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 LCRA Expansion Agreement In January 2025, the Company entered into the second agreement with Lower Colorado River Authority (“LCRA”) to sell 900 MHz Broadband Spectrum licenses covering 34 additional counties in its service area, building upon the 68 counties covered by the first LCRA agreement for total estimated consideration of $13.5 million. Oncor Agreement In June 2024, the Company entered into an agreement with Oncor Electric Delivery Company LLC (“Oncor”) to sell 900 MHz Broadband covering 95 counties to deploy a private wireless broadband network in its transmission and distribution service area for total estimated consideration of $102.5 million (the “Oncor Agreement”). The total payment of $102.5 million comprises an initial payment of $10.0 million received in June 2024 with remaining payments due to the Company for each county, at closing. The timing and rights to milestone payments could vary as 900 MHz broadband licenses are granted by the Federal Communications Commission (the “FCC”), broadband licenses are assigned to Oncor and incumbents are cleared by the Company. Oncor operates more than 143,000 circuit miles of transmission and distribution lines in Texas, delivering electricity to more than four million homes and businesses across a service territory that has an estimated population of approximately 13 million people. See Note 15 Contingencies and Guaranty for further discussion on the Oncor Agreement. Corporate Developments Executive Chairman Transition In December 2024, the Company announced Morgan O’Brien’s retirement as a director, as Executive Chairman of the Board of Directors of the Company (the “Board”), and as an executive of the Company, each effective as of December 31, 2024. In addition, the Company entered into a consulting agreement with Mr. O’Brien. See Note 10 Related Party Transactions for further discussion. The Company appointed Thomas R. Kuhn, as the Chairman of the Board (the “Board Chair”), effective January 1, 2025. The Board also appointed Mr. Kuhn as the Chair of the newly established Utility Engagement Committee. This committee is responsible for overseeing and strengthening the Company's relationships and commercialization efforts within the utility industry. Subsequently, on January 22, 2025, the Company entered into an employment agreement with Mr. Kuhn naming him as Executive Chairman (the “Employment Agreement”). Due to his appointment as an executive of the Company, effective as of the date of his appointment, Mr. Kuhn resigned from serving on the Board’s Compensation Committee, Audit Committee and Nominating and Governance Committee. Chief Executive Officer Transition On October 8, 2024, the Company announced the appointment of Scott Lang as President and Chief Executive Officer, to succeed Robert Schwartz effective by November 1, 2024 (the “CEO Transition”). As part of the CEO Transition, the Board also designated Mr. Lang as the Company’s principal executive officer for purposes of the rules and regulations of the U.S Securities and Exchange Commission (the “SEC”) by reference to Exhibit 10.2 to the Company’s Quarterly Report on Form 10-Q, filed with the SEC on November 13, 2024. Due to his service as an executive of the Company, effective as of the date of his appointment, Mr. Lang resigned from serving on the Board’s Audit Committee and Nominating and Governance Committee.