Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reconciliation of information used in computing basic and diluted earnings per share [Abstract]
Earnings from continuing operations	$ 294,352	$ 205,156	$ 491,341	$ 391,565
Earnings from discontinued operations, net	35,697	8,945	48,711	18,599
Net earnings	$ 330,049	$ 214,101	$ 540,052	$ 410,164
Basic earnings (loss) per common share:
Earnings from continuing operations (in dollars per basic share)	$ 1.72	$ 1.12	$ 2.85	$ 2.13
Earnings from discontinued operations, net (in dollars per basic share)	$ 0.21	$ 0.05	$ 0.28	$ 0.10
Net earnings (in dollars per basic share)	$ 1.93	$ 1.17	$ 3.13	$ 2.23
Weighted average shares outstanding - basic (in shares)	171,111,000	183,494,000	172,273,000	183,625,000
Diluted earnings (loss) per common share:
Earnings from continuing operations (in dollars per diluted share)	$ 1.70	$ 1.10	$ 2.82	$ 2.10
Earnings from discontinued operations, net (in dollars per diluted share)	$ 0.21	$ 0.05	$ 0.28	$ 0.10
Net earnings (in dollars per diluted share)	$ 1.91	$ 1.15	$ 3.10	$ 2.20
Weighted average shares outstanding - diluted (in shares)	173,097,000	185,780,000	174,325,000	186,171,000
Reconciliation Of Share Amounts Used In Computing Earnings Per Share [Abstract]
Weighted average shares outstanding - basic (in shares)	171,111,000	183,494,000	172,273,000	183,625,000
Dilutive effect of assumed exercise of employee stock options, SAR's and performance shares (in shares)	1,986,000	2,286,000	2,052,000	2,546,000
Weighted average shares outstanding - diluted (in shares)	173,097,000	185,780,000	174,325,000	186,171,000
Weighted average number of anti-dilutive potential common shares excluded from reconciliation calculations (in shares)	1,590,000	3,135,000	1,206,000	2,784,000