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, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Quarterly Financial Information [Line Items]
Total revenues				$ 23,286	$ 23,898	$ 24,755	$ 22,632	$ 23,573	$ 25,849	$ 24,543	$ 22,149	$ 94,571	$ 96,114	$ 90,762
Total costs and expenses				(19,464)	(19,904)	(22,325)	(19,097)	(20,642)	(21,600)	(21,350)	(18,496)	(80,790)	(82,088)	(76,752)
Earnings from operations				2,183	2,282	(419)	1,788	1,161	2,580	1,683	2,019	5,834	7,443	7,473
Net earnings				$ 1,631	$ 2,279	$ (234)	$ 1,219	$ 1,026	$ 1,704	$ 1,110	$ 1,336	$ 4,895	$ 5,176	$ 5,446
Basic earnings per share				$ 2.63	$ 3.64	$ (0.37)	$ 1.85	$ 1.52	$ 2.50	$ 1.61	$ 1.89	$ 7.70	$ 7.52	$ 7.47
Diluted earnings per share				2.59	3.60	(0.37)	1.83	1.51	2.47	1.59	1.87	7.61	7.44	7.38
Cash dividends declared, per share	$ 1.42	$ 1.09	$ 0.91	2.51		2.18		2.00		1.82		4.69	3.82	$ 3.10
Common stock sales price per share, Quarter end	$ 155.68	$ 144.59		155.68	131.74	129.87	126.94	144.59	130.95	138.72	150.08	$ 155.68	$ 144.59
Maximum [Member]
Schedule of Quarterly Financial Information [Line Items]
Common stock sales price per share				160.07	139.45	137.89	141.70	150.59	149.18	155.50	158.83
Minimum [Member]
Schedule of Quarterly Financial Information [Line Items]
Common stock sales price per share				$ 130.74	$ 123.96	$ 122.35	$ 102.10	$ 128.56	$ 115.14	$ 138.44	$ 126.18