Quarterly Financial Data (Schedule Of Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			3 Months Ended								12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Quarterly Financial Information [Line Items]
Total revenues				$ 25,368	$ 24,309	$ 22,739	$ 20,976	$ 23,286	$ 23,898	$ 24,755	$ 22,632	$ 93,392	$ 94,571	$ 96,114
Total costs and expenses				(20,427)	(19,987)	(18,388)	(17,264)	(19,464)	(19,904)	(22,325)	(19,097)	(76,066)	(80,790)	(82,088)
Earnings from operations				3,030	2,689	2,535	2,024	2,183	2,282	(419)	1,788	10,278	5,834	7,443
Net earnings				$ 3,132	$ 1,853	$ 1,761	$ 1,451	$ 1,631	$ 2,279	$ (234)	$ 1,219	$ 8,197	$ 4,895	$ 5,176
Basic earnings per share				$ 5.25	$ 3.10	$ 2.93	$ 2.36	$ 2.63	$ 3.64	$ (0.37)	$ 1.85	$ 13.60	$ 7.70	$ 7.52
Diluted earnings/(loss) per share				5.18	3.06	2.89	2.34	2.59	3.60	(0.37)	1.83	13.43	7.61	7.44
Cash dividends declared, per share	$ 1.71	$ 1.42	$ 1.09	3.13		2.84		2.51		2.18		5.97	4.69	$ 3.82
Common stock sales price per share, Quarter end	$ 294.91	$ 155.68		294.91	254.21	197.75	176.86	155.68	131.74	129.87	126.94	$ 294.91	$ 155.68
Maximum [Member]
Schedule of Quarterly Financial Information [Line Items]
Common stock sales price per share				299.33	259.30	204.39	185.71	160.07	139.45	137.89	141.70
Minimum [Member]
Schedule of Quarterly Financial Information [Line Items]
Common stock sales price per share				$ 253.53	$ 197.75	$ 175.47	$ 155.21	$ 130.74	$ 123.96	$ 122.35	$ 102.10