Non-U.S. Activities - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Segment Reporting Information [Line Items]
Total assets	$ 280,242	$ 245,610
Non-U.S.
Segment Reporting Information [Line Items]
Total assets	$ 94,290		$ 85,940