NorthWestern Corporation, doing business as North-Western Energy provides electricity and natural gas. The Company's segments include electric utility operations and natural gas utility operations. The electric utility operations segment includes the generation, purchase, transmission and distribution of electricity. The natural gas utility operations segment includes the production, purchase, transmission, storage, and distribution of natural gas. Its electric utility business in Montana includes generation, transmission and distribution and provides electricity to approximately 384,700 customers in 208 communities. Its South Dakota electric utility business provides retail electricity to more than 63,900 customers in 110 communities in South Dakota. Its regulated natural gas utility business in Montana includes production, storage, transmission and distribution. It distributes natural gas to approximately 203,700 customers in 118 Montana communities.