Basic and Diluted Earnings Per Share (Details) (USD $) In Thousands, except Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Reconciliation of basic and diluted earnings per share
Net earnings from continuing operations	$ 54,333	$ 42,594	$ 133,316	$ 101,103
Earnings from discontinued operations, net		1,510		4,554
Net earnings	$ 54,333	$ 44,104	$ 133,316	$ 105,657
Basic shares:
Average shares outstanding	51,900,000	51,602,000	51,772,000	51,863,000
Basic earnings per share:
Continuing operations	$ 1.05	$ 0.83	$ 2.58	$ 1.95
Discontinued operations		$ 0.02		$ 0.09
Net earnings	$ 1.05	$ 0.85	$ 2.58	$ 2.04
Diluted shares:
Average shares outstanding	51,900,000	51,602,000	51,772,000	51,863,000
Additional shares on the potential dilution from stock options, nonvested restricted stock and performance units	1,090,000	1,039,000	1,336,000	1,049,000
Number of diluted shares outstanding	52,990,000	52,641,000	53,108,000	52,912,000
Diluted earnings per share:
Continuing operations	$ 1.03	$ 0.81	$ 2.51	$ 1.91
Discontinued operations		$ 0.03		$ 0.09
Net earnings	$ 1.03	$ 0.84	$ 2.51	$ 2.00
Basic and Diluted Earnings Per Share (Textual)
Out-of-the money stock options associated with common stock that were anti-dilutive	700,000	1,800,000	300,000	1,800,000