Earnings per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Reconciliation of information used in computing basic and diluted earnings per share [Abstract]
Earnings from continuing operations	$ 196,989	$ 186,409
Earnings from discontinued operations, net	13,014	9,654
Net earnings	$ 210,003	$ 196,063
Basic earnings (loss) per common share:
Earnings from continuing operations (in dollars per basic share)	$ 1.14	$ 1.01
Earnings (loss) from discontinued operations, net (in dollars per basic share)	$ 0.08	$ 0.05
Net earnings (in dollars per basic share)	$ 1.21	$ 1.07
Weighted average shares outstanding - basic (in shares)	173,448	183,737
Diluted earnings (loss) per common share:
Earnings from continuing operations (in dollars per diluted share)	$ 1.12	$ 1.00
Earnings (loss) from discontinued operations, net (in dollars per diluted share)	$ 0.07	$ 0.05
Net earnings (in dollars per diluted share)	$ 1.20	$ 1.05
Weighted average shares outstanding - diluted (in shares)	175,567	186,706
Reconciliation Of Share Amounts Used In Computing Earnings Per Share [Abstract]
Weighted average shares outstanding - basic (in shares)	173,448	183,737
Dilutive effect of assumed exercise of employee stock options, SAR's and performance shares (in shares)	2,119	2,969
Weighted average shares outstanding - diluted (in shares)	175,567	186,706
Weighted average number of anti-dilutive potential common shares excluded from reconciliation calculations (in shares)	2,501	2,437