Commitment and Contingencies - Narrative - (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Assets	$ 504,336	$ 473,078
Other Liabilities	11,385	12,236
Trading assets at fair value	3,824	5,733
Variable Interest Entity, Primary Beneficiary [Member]
Other Commitments [Line Items]
Assets	1,600	2,700
Other Liabilities	95	116
Trading assets at fair value	1,500	$ 2,600
Min
Loss Contingency [Abstract]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	0
Max
Loss Contingency [Abstract]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	$ 200