Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Abstract]

Major categories of property, plant and equipment and accumulated depreciation and depletion

     The major categories of property, plant and equipment and accumulated depreciation and depletion are presented below:

Thousands of Dollars		2012			2011
Land	$	26,467		$	27,370
Quarries/mining properties		39,596			39,596
Buildings		145,082			147,115
Machinery and equipment		937,559			911,753
Construction in progress		27,805			31,060
Furniture and fixtures and other		85,443			91,755
		1,261,952			1,248,649
Less: Accumulated depreciation and depletion		(944,283	)		(930,515	)
Property, plant and equipment, net	$	317,669		$	318,134