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MATERIALS, SUPPLIES, AND INVENTORIES (Tables)
9 Months Ended
Sep. 30, 2021
Inventory Disclosure [Abstract]  
Schedule of inventory
Our inventory consisted of:
(in millions)September 30, 2021December 31, 2020
Natural gas in storage$365.3 $224.9 
Materials and supplies229.0 218.1 
Fossil fuel51.4 85.6 
Total$645.7 $528.6