Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Assets [Abstract]
Goodwill	$ 3,852	$ 3,315	$ 3,072
Other intangible assets, at amortized cost	265	267
Other	13,562	10,635
Total	$ 17,679	$ 14,217