Pinnacle West Capital Corporation is a holding company that operates through its subsidiaries. The Company operates through regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses and related activities, and includes electricity generation, transmission and distribution. It owned and leased 6,236 megawatt (MW) of regulated generation capacity and the Company held a mix of both long-term and short-term purchased power agreements for additional capacity, including agreements for the purchase of renewable energy, as of December 31, 2016. Its subsidiaries include Arizona Public Service Company, which is a vertically-integrated electric utility that provides retail or wholesale electric service to the State of Arizona, with the exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona.