Non-U.S. Activities - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total assets	$ 272,075	$ 245,610
Non-U.S.
Segment Reporting Information [Line Items]
Total assets	$ 92,330		$ 81,620