Nature of Operations	12 Months Ended
Nature of Operations	Mar. 31, 2024
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 TECO Agreement In November 2023, the Company entered into an agreement with Tampa Electric Company (“TECO”) to provide TECO the use of the Company’s 900 MHz Broadband Spectrum for a term of 20 years throughout TECO’s service territory in West Central Florida (the “TECO Agreement”). The TECO Agreement also provides TECO an option to extend the agreement for two 10-year terms for additional payments. The TECO Agreement, which covers an approximately 2,000-square-mile service territory in West Central Florida, is expected to enable TECO to deploy a PLTE network providing critical broadband communications capabilities in support of its initiatives. The scheduled prepayments for the 20-year initial term of the TECO Agreement total $34.5 million, of which $6.9 million was received by the Company in December 2023. See Note 3 Revenue for further discussion on the TECO Agreement. LCRA Agreement In April 2023, the Company entered into an agreement with Lower Colorado River Authority (“LCRA”) to sell 900 MHz Broadband Spectrum covering 68 counties and more than 30 cities in LCRA’s wholesale electric, transmission, and water service area (the “LCRA Agreement”) for total payments of $30.0 million plus the contribution of select LCRA 900 MHz narrowband spectrum. Total consideration of $30.0 million is to be paid through fiscal year 2026 pursuant to the terms of the LCRA Agreement. During the year ended March 31, 2024, the Company received an initial $15.0 million payment, of which $7.5 million was deposited in an escrow account (refer to Note 4 Escrow Deposits for further discussion). See Note 13 Contingencies and Guaranty for further discussion on the LCRA Agreement. Xcel Energy Agreement In October 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”) for a total of $80.0 million, of which $8.0 million was received by the Company in December 2022. In July 2023 and November 2023, the Company delivered the cleared 900 MHz Broadband Spectrum and the associated broadband leases and received milestone payments of $21.2 million in each period. During the year ended March 31, 2024, the Company delivered the cleared 900 MHz Broadband Spectrum and the associated broadband leases and received a milestone payment of $16.8 million in January 2024. The revenue recognized for the year ended March 31, 2024, was approximately $1.9 million. SDG&E Agreement In February 2021, the Company entered into an agreement with San Diego Gas & Electric Company, a subsidiary of Sempra Energy (“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 total payment of $50.0 million is comprised of an initial payment of $20.0 million received in February 2021 and the remaining payments which are due as the Company delivers the relevant cleared 900 MHz Broadband Spectrum and the associated broadband licenses to SDG&E. In September 2023, the Company transferred to SDG&E the San Diego County broadband license and received a milestone payment of $25.2 million net of delivery delay adjustments of $1.1 million. In December 2023, the Company transferred to SDG&E the remainder of the 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 6 Intangible Assets for further discussion. 2023 Stock Plan On August 8, 2023, the Company adopted a new equity-based compensation plan known as the Anterix Inc. 2023 Stock Plan (the “2023 Stock Plan”). The 2023 Stock Plan permits the Company to grant equity compensation awards to employees, consultants and non-employee directors of the Company. See Note 11 Stock Compensation for further discussion. 2023 Share Repurchase Program On September 21, 2023, the Board of Directors (the “Board”) authorized a new share repurchase program (the “2023 Share Repurchase Program”) pursuant to which the Company may repurchase up to $250.0 million of the Company’s common stock on or before September 21, 2026. See Note 11 Stock Compensation for further discussion.