Investments, Loans and Long-Term Receivables (Summary of Financial Information for Equity Method Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of financial information
Revenues	$ 38,156	$ 43,627	$ 35,523
Income before income taxes	4,976	6,066	3,956
Net income	4,787	5,926	3,764
Current assets	6,654	6,791	7,325
Noncurrent assets	56,163	52,649	49,950
Current liabilities	6,094	8,047	5,248
Noncurrent liabilities	15,740	10,695	13,743
Noncontrolling interests	$ 2,145	$ 2,550	$ 2,549