Black Hills Corporation is a holding company. The Company is an integrated energy company, which is focused primarily on regulated utilities. The Company operates through segments, including Electric Utilities, Gas Utilities, Power Generation, Mining, Oil and Gas, and Corporate. As of December 31, 2016, the Electric Utilities segment generated, transmitted and distributed electricity to approximately 208,500 customers in South Dakota, Wyoming, Colorado and Montana. The Gas Utilities Segment includes the natural gas operations of Cheyenne Light. The Power Generation segment produces electric power from its generating plants and sells the electric capacity and energy principally to its utilities under long-term contracts. The Mining segment operates through its Wyodak Resources Development Corp. (WRDC) subsidiary. The Company's Oil and Gas segment acquires, explores for, develops and produces natural gas and crude oil in the United States primarily in the Rocky Mountain region.