Inventories (Tables)

12 Months Ended

Dec. 31, 2012

Inventory Disclosure [Abstract]

Summary of Inventories

Inventories on the Consolidated Balance Sheets are summarized as follows:

	December 31,
(Thousands)	2012		2011
Principally average cost:
Raw materials and supplies	$	42,751	$	42,969
Work in process	203,179		179,445
Finished goods	51,094		57,645
Gross inventories	297,024		280,059
Excess of average cost over LIFO inventory value	90,899		92,883
Net inventories	$	206,125	$	187,176