MDU Resources Group, Inc. is a natural resource company. The Company’s segments include electric, natural gas distribution, pipeline and energy services, exploration and production, construction materials and contracting and construction services. The electric segment provides electric service at retail. The natural gas distribution segment sells natural gas at retail. The pipeline and energy services segment through WBI Holdings, Inc. owns and operates both regulated and nonregulated businesses. The exploration and production segment is involved in the development and production of oil and natural gas resources. The construction materials and contracting segment mines aggregates and markets crushed stone, sand, gravel and related construction materials. The construction services segment is engaged in constructing and maintaining electric and communication lines, gas pipelines, fire suppression systems, and external lighting and traffic signalization equipment.