The commission shall have power, upon a hearing, had upon its own motion or upon complaint, to investigate a single rate, fare, toll, rental, charge, classification, rule, regulation, contract or practice, or any number thereof, or the entire schedule or schedules of rates, fares, tolls, rentals, charges, classifications, rules, regulations, contracts or practices, or any thereof, of any public utility, and to establish new rates, fares, tolls, rentals, charges, classifications, rules, regulations, contracts or practices or schedule or schedules in lieu thereof.
Idaho Code § 61-503