Net Earnings Per Share Net Earnings Per Share (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator for earnings per share:
Earnings from continuing operations	$ 46,486	$ 55,949	$ 148,280	$ 147,179
Loss from discontinued operations	0	(44)	0	(2,042)
Net earnings for basic and diluted earnings per share	$ 46,486	$ 55,905	$ 148,280	$ 145,137
Denominator for earnings per share:
Weighted average number of common shares outstanding	141,863	150,878	142,849	152,820
Assumed exercises of stock options and vesting of restricted stock awards, net of shares assumed reacquired under the treasury stock method	2,368	1,449	1,982	1,938
Weighted average diluted shares outstanding	144,231	152,327	144,831	154,758