Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reconciliation of information used in computing basic and diluted earnings per share [Abstract]
Earnings from continuing operations	$ 155,634	$ 210,581	$ 272,824	$ 380,622
Earnings (loss) from discontinued operations, net	176,762	3,378	269,082	(6,525)
Net earnings	$ 332,396	$ 213,959	$ 541,906	$ 374,097
Basic earnings (loss) per common share:
Earnings from continuing operations (in dollars per basic share)	$ 0.98	$ 1.26	$ 1.70	$ 2.26
Earnings (loss) from discontinued operations, net (in dollars per basic share)	1.11	0.02	1.68	(0.04)
Net earnings (in dollars per basic share)	$ 2.10	$ 1.29	$ 3.38	$ 2.23
Weighted average shares outstanding - basic (in shares)	158,640,000	166,474,000	160,137,000	168,103,000
Diluted earnings (loss) per common share:
Earnings from continuing operations (in dollars per diluted share)	$ 0.97	$ 1.25	$ 1.69	$ 2.23
Earnings (loss) from discontinued operations, net (in dollars per diluted share)	1.10	0.02	1.66	(0.04)
Net earnings (in dollars per diluted share)	$ 2.07	$ 1.27	$ 3.35	$ 2.19
Weighted average shares outstanding - diluted (in shares)	160,398,000	168,857,000	161,876,000	170,450,000
Reconciliation Of Share Amounts Used In Computing Earnings Per Share [Abstract]
Weighted average shares outstanding - basic (in shares)	158,640,000	166,474,000	160,137,000	168,103,000
Dilutive effect of assumed exercise of employee stock options, SAR's and performance shares (in shares)	1,758,000	2,383,000	1,739,000	2,347,000
Weighted average shares outstanding - diluted (in shares)	160,398,000	168,857,000	161,876,000	170,450,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	45,000	48,000	35,000	0