WGL Holdings, Inc., through its subsidiaries, sells and delivers natural gas; and provides energy-related products and services. The company operates through four segments: Regulated Utility, Retail Energy-Marketing, Commercial Energy Systems, and Midstream Energy Services. The Regulated Utility segment sells and delivers natural gas to retail customers; and owns full and partial interests in underground natural gas storage facilities, including pipeline delivery facilities located in and around Hampshire County, West Virginia. The Retail Energy-Marketing segment sells natural gas and electricity directly to residential, commercial, and industrial customers. The Commercial Energy Systems segment provides clean and energy efficient solutions, including commercial solar, energy efficiency, and combined heat and power projects, as well as other distributed generation solutions to government and commercial clients. This segment also focuses on upgrading the mechanical, electrical, and water and energy-related infrastructure of governmental and commercial facilities by implementing traditional and alternative energy technologies. The Midstream Energy Services segment acquires, invests in, manages, and optimizes natural gas storage and transportation assets. As of September 30, 2017, the company had approximately 577 miles of transmission mains; 13,103 miles of distribution mains; and 12,518 miles of distribution services, as well as served approximately 116,200 natural gas customers and approximately 113,700 electricity customers in Maryland, Virginia, Delaware, Pennsylvania, and the District of Columbia. WGL Holdings, Inc. was founded in 1848 and is based in Washington, the District of Columbia. As of July 6, 2018, WGL Holdings, Inc. operates as a subsidiary of AltaGas Ltd.