Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Selected Quarterly Financial Data [Line Items]
Total revenues	$ 39,715	$ 36,990	$ 38,853	$ 40,342	$ 41,793	$ 37,666	$ 38,920	$ 41,959	$ 155,900	$ 160,338	$ 156,776
Income/(Loss) before income taxes	(2,436)	(19)	205	1,610	(17)	1,094	1,349	1,919	(640)	4,345	8,159
Net Income (Loss) Available to Common Stockholders, Basic	$ (1,672)	$ 425	$ 148	$ 1,146	$ (116)	$ 991	$ 1,066	$ 1,736	47	3,677	7,731
Basic Common and Class B per share income from continuing operations	$ (0.42)	$ 0.11	$ 0.04	$ 0.29	$ (0.03)	$ 0.25	$ 0.27	$ 0.44
Diluted Common and Class B per share income from continuing operations	$ (0.42)	$ 0.11	$ 0.04	$ 0.29	$ (0.03)	$ 0.25	$ 0.27	$ 0.43
UNITED STATES
Selected Quarterly Financial Data [Line Items]
Total revenues									98,729	97,546	93,844
Income/(Loss) before income taxes									2,656	2,051	4,861
Non-US
Selected Quarterly Financial Data [Line Items]
Income/(Loss) before income taxes									$ (3,296)	$ 2,294	$ 3,298
Pension Plan
Material unusual or infrequently occurring items: [Abstract]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	$ (2,200)	$ (306)			$ (877)
Accelerated depreciation, separations, and payments | Global Redesign
Material unusual or infrequently occurring items: [Abstract]
Restructuring Charges	$ 413	1,000	$ 1,200	$ 514
Other Nonrecurring (Income) Expense		$ 278