MDU Resources Group, Inc. is a diversified natural resource company that operates in six segments: electric; natural gas distribution; utility services; pipeline and energy services; natural gas and oil production, and construction materials and mining. The electric and natural gas distribution segments include the electric and natural gas distribution operations of Montana-Dakota Utilities Co. and the natural gas distribution operations of Great Plains Natural Gas Co. The utility services segment includes all the operations of Utility Services, Inc. The pipeline and energy services segment includes WBI Holdings, Inc.'s natural gas transportation, underground storage, gathering services and energy-related management services. The natural gas and oil production segment includes the natural gas and oil acquisition, exploration and production operations of WBI Holdings. The construction materials and mining segment includes the results of Knife River Corporation's operations.01