INVENTORIES

Inventories consisted of the following:



	September 30, 2018			December 31, 2017			September 30, 2017
	($ in millions)
Supplies	$	63.7		$	66.1		$	60.3
Raw materials	70.1			75.3			85.4
Work in process	155.9			127.8			120.6
Finished goods	493.6			462.6			470.7
	783.3			731.8			737.0
LIFO reserve	(58.9		)	(49.2		)	(47.5		)
Inventories, net	$	724.4		$	682.6		$	689.5

Inventories are valued at the lower of cost and net realizable value. For U.S. inventories, inventory costs are determined principally by the last-in, first-out (LIFO) method of inventory accounting while for international inventories, inventory costs are determined principally by the first-in, first-out (FIFO) method of inventory accounting. Cost for other inventories has been determined principally by the average-cost method (primarily operating supplies, spare parts and maintenance parts). Elements of costs in inventories included raw materials, direct labor and manufacturing overhead. Inventories under the LIFO method are based on annual estimates of quantities and costs as of year-end; therefore, the condensed financial statements at September 30, 2018 reflect certain estimates relating to inventory quantities and costs at December 31, 2018. The replacement cost of our inventories would have been approximately $58.9 million, $49.2 million and $47.5 million higher than reported at September 30, 2018, December 31, 2017 and September 30, 2017, respectively.