Condensed Consolidating Financial Statements (Condensed Consolidating Statement Of Earnings) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Consolidating Financial Statements [Line Items]
Revenues	$ 32,677	$ 32,466	$ 31,981
Operating costs	26,821	26,557	26,352
General and administrative expenses	2,030	1,964	1,954
Operating earnings	3,826	3,945	3,675
Interest expense	(155)	(167)	(171)
Interest income	14	10	11
Other, net	33	2	(2)
Earnings from continuing operations before income taxes	3,718	3,790	3,513
Provision for income taxes	1,166	1,162	1,106
Discontinued operations, net of tax	(26)	(4)	(13)
Net earnings	2,526	2,624	2,394
Parent [Member]
Condensed Consolidating Financial Statements [Line Items]
Operating costs	(13)	1	9
General and administrative expenses	90	82	83
Operating earnings	(77)	(83)	(92)
Interest expense	(152)	(164)	(163)
Interest income	9	3	2
Other, net	5	1	(1)
Earnings from continuing operations before income taxes	(215)	(243)	(254)
Provision for income taxes	(43)	(78)	(35)
Equity in net earnings of subsidiaries	2,698	2,789	2,613
Net earnings	2,526	2,624	2,394
Guarantors On A Combined Basis [Member]
Condensed Consolidating Financial Statements [Line Items]
Revenues	26,253	26,376	25,765
Operating costs	21,336	21,558	21,143
General and administrative expenses	1,499	1,497	1,495
Operating earnings	3,418	3,321	3,127
Interest expense	(2)	(2)	(3)
Interest income	2	3	4
Other, net	27	1	(2)
Earnings from continuing operations before income taxes	3,445	3,323	3,126
Provision for income taxes	1,097	1,067	1,010
Net earnings	2,348	2,256	2,116
Other Subsidiaries On A Combined Basis [Member]
Condensed Consolidating Financial Statements [Line Items]
Revenues	6,424	6,090	6,216
Operating costs	5,498	4,998	5,200
General and administrative expenses	441	385	376
Operating earnings	485	707	640
Interest expense	(1)	(1)	(5)
Interest income	3	4	5
Other, net	1		1
Earnings from continuing operations before income taxes	488	710	641
Provision for income taxes	112	173	131
Discontinued operations, net of tax	(26)	(4)	(13)
Net earnings	350	533	497
Consolidating Adjustments [Member]
Condensed Consolidating Financial Statements [Line Items]
Equity in net earnings of subsidiaries	(2,698)	(2,789)	(2,613)
Net earnings	$ (2,698)	$ (2,789)	$ (2,613)