Inventories	12 Months Ended
Dec. 31, 2012
Inventories
Inventories	Note 4. Inventories Our inventories have primarily been stated on the last-in, first-out ("LIFO") method, which is not in excess of market. We use the LIFO method of inventory valuation because it results in a better matching of costs and revenues. As of December 31, 2012 and 2011, cost on the first-in, first-out ("FIFO") method exceeded the LIFO value of inventories by $138.8 million and $202.9 million, respectively. Inventories of $243.7 million and $237.0 million as of December 31, 2012 and 2011, respectively, were stated on the FIFO method, which is not in excess of market. In 2012, cost decreases for the majority of our products were the primary cause of the $64.1 million reduction of the LIFO valuation reserve, which lowered cost of sales. Cost increases in 2011 and 2010 for the majority of our products were the primary cause of the $85.3 million and $34.8 million increase in the LIFO valuation reserve, respectively, which increased cost of sales. In 2012, 2011 and 2010 we generally increased our tons on-hand levels due to increased shipment levels. Consequently, there were insignificant liquidations of LIFO inventory quantities in 2012, 2011 and 2010.

Inventories

12 Months Ended

Dec. 31, 2012

Note 4. Inventories

Our inventories have primarily been stated on the last-in, first-out ("LIFO") method, which is not in excess of market. We use the LIFO method of inventory valuation because it results in a better matching of costs and revenues. As of December 31, 2012 and 2011, cost on the first-in, first-out ("FIFO") method exceeded the LIFO value of inventories by $138.8 million and $202.9 million, respectively. Inventories of $243.7 million and $237.0 million as of December 31, 2012 and 2011, respectively, were stated on the FIFO method, which is not in excess of market.

In 2012, cost decreases for the majority of our products were the primary cause of the $64.1 million reduction of the LIFO valuation reserve, which lowered cost of sales. Cost increases in 2011 and 2010 for the majority of our products were the primary cause of the $85.3 million and $34.8 million increase in the LIFO valuation reserve, respectively, which increased cost of sales. In 2012, 2011 and 2010 we generally increased our tons on-hand levels due to increased shipment levels. Consequently, there were insignificant liquidations of LIFO inventory quantities in 2012, 2011 and 2010.