Inventories - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Inventories [Line Items]
Inventories classified as long-term assets (Other noncurrent assets)	$ 35,477,000	$ 19,726,000
Inventories valued under the LIFO method	267,591,000	251,978,000
Decrease in cost of goods sold due to the effect of the LIFO liquidation	1,124,000	1,288,000	2,956,000
Increase in net earnings due to the effect of the LIFO liquidation	688,000	776,000	1,763,000
Excess of estimated current cost over LIFO cost	150,654,000	140,335,000
Approximate effect on net earnings due to the adoption of the LIFO method	$ 5,990,000	$ 10,050,000	$ (3,890,000)