Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues	$ 489,383	$ 523,822	$ 1,467,792	$ 1,582,645
Costs and expenses:
Cost of sales	361,337	388,284	1,086,648	1,180,905
Selling, general and administrative	74,577	73,358	228,632	234,498
Amortization expense	3,729	3,245	11,187	9,557
Goodwill impairment (Note 10)	0	0	0	7,585
Total costs and expenses	439,643	464,887	1,326,467	1,432,545
Earnings (loss) from operations	49,740	58,935	141,325	150,100
Other expenses and income:
Interest expense	7,287	7,563	22,464	21,372
Interest income	(30)	(46)	(138)	(174)
Other income, net	(1,713)	249	(2,636)	(525)
Total other expenses (income), net	5,544	7,766	19,690	20,673
Earnings (loss) before income taxes	44,196	51,169	121,635	129,427
Income tax expense (Note 1)	16,483	14,429	45,467	44,559
Net earnings	$ 27,713	$ 36,740	$ 76,168	$ 84,868
Net earnings per common share, basic (Note 6)	$ 0.73	$ 0.94	$ 1.98	$ 2.08
Net earnings per common share, diluted (Note 6)	$ 0.70	$ 0.90	$ 1.91	$ 2.00
Weighted-average common shares outstanding, basic (Note 6)	37,460	39,047	37,818	40,777
Weighted-average common shares outstanding, diluted (Note 6)	38,684	40,832	39,147	42,532
Common Stock, Dividends, Per Share, Declared	$ 0.31	$ 0	$ 0.93	$ 0