Segment Disclosures and Related Information (Summary of Geographic Information) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Worldwide consolidated	$ 38,357	$ 36,439	$ 35,401
United States
Segment Reporting Information [Line Items]
Worldwide consolidated	36,407	34,587	33,457
United Kingdom
Segment Reporting Information [Line Items]
Worldwide consolidated	1,256	1,191	1,254
Germany
Segment Reporting Information [Line Items]
Worldwide consolidated	601	570	593
Other foreign countries
Segment Reporting Information [Line Items]
Worldwide consolidated	$ 93	$ 91	$ 97