Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reconciliation of information used in computing basic and diluted earnings per share [Abstract]
Earnings from continuing operations	$ 263,652	$ 233,330	$ 754,993	$ 624,895
Earnings from discontinued operations, net	5,462	7,716	54,173	26,315
Net earnings	$ 269,114	$ 241,046	$ 809,166	$ 651,210
Basic earnings (loss) per common share:
Earnings from continuing operations (in dollars per basic share)	$ 1.55	$ 1.28	$ 4.40	$ 3.41
Earnings from discontinued operations, net (in dollars per basic share)	$ 0.03	$ 0.04	$ 0.32	$ 0.14
Net earnings (in dollars per basic share)	$ 1.58	$ 1.33	$ 4.71	$ 3.56
Weighted average shares outstanding - basic (in shares)	170,544,000	181,763,000	171,690,000	183,000,000
Diluted earnings (loss) per common share:
Earnings from continuing operations (in dollars per diluted share)	$ 1.53	$ 1.27	$ 4.34	$ 3.37
Earnings from discontinued operations, net (in dollars per diluted share)	$ 0.03	$ 0.04	$ 0.31	$ 0.14
Net earnings (in dollars per diluted share)	$ 1.56	$ 1.31	$ 4.65	$ 3.51
Weighted average shares outstanding - diluted (in shares)	172,734,000	183,932,000	173,870,000	185,489,000
Reconciliation Of Share Amounts Used In Computing Earnings Per Share [Abstract]
Weighted average shares outstanding - basic (in shares)	170,544,000	181,763,000	171,690,000	183,000,000
Dilutive effect of assumed exercise of employee stock options, SAR's and performance shares (in shares)	2,190,000	2,169,000	2,180,000	2,489,000
Weighted average shares outstanding - diluted (in shares)	172,734,000	183,932,000	173,870,000	185,489,000
Weighted average number of anti-dilutive potential common shares excluded from reconciliation calculations (in shares)	0	3,128,000	0	2,899,000