Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	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
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 16,070	$ 14,827	$ 14,943	$ 14,988	$ 16,501	$ 15,832	$ 15,629	$ 14,384	$ 60,828	$ 62,346	$ 67,702
Gross Profit	939	812	887	868	1,011	1,090	737	781	3,506	3,619	3,966
Net Earnings Attributable to Controlling Interests	$ 788	$ 192	$ 276	$ 339	$ 424	$ 341	$ 284	$ 230	$ 1,595	$ 1,279	$ 1,849
Basic earnings per common share (dollars per share)	$ 1.40	$ 0.34	$ 0.48	$ 0.59	$ 0.73	$ 0.58	$ 0.48	$ 0.39	$ 2.80	$ 2.18	$ 2.99
Diluted earnings per common share (dollars per share)	$ 1.39	$ 0.34	$ 0.48	$ 0.59	$ 0.73	$ 0.58	$ 0.48	$ 0.39	$ 2.79	$ 2.16	$ 2.98