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MATERIALS, SUPPLIES, AND INVENTORIES
 9 Months Ended
Sep. 30, 2023
Inventory Disclosure [Abstract]  
MATERIALS, SUPPLIES, AND INVENTORIES MATERIALS, SUPPLIES, AND INVENTORIES
Our inventories consisted of:
(in millions)September 30, 2023December 31, 2022
Natural gas in storage$353.2 $446.3 
Materials and supplies301.7 257.0 
Fossil fuel95.0 103.8 
Total$749.9 $807.1 
PGL and NSG price natural gas storage injections at the calendar year average of the costs of natural gas supply purchased. Withdrawals from storage are priced on the LIFO cost method. For interim periods, the difference between current projected replacement cost and the LIFO cost for quantities of natural gas temporarily withdrawn from storage is recorded as a temporary LIFO liquidation debit or credit. At September 30, 2023, all LIFO layers were replenished, and the LIFO liquidation balance was zero.

Substantially all other natural gas in storage, materials and supplies, and fossil fuel inventories are recorded using the weighted-average cost method of accounting.