Commitment and Contingencies - Narrative - (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entities
Trading Assets	$ 5,733,000,000	$ 391,000,000
Total assets	473,078,000,000	225,697,000,000
Other Liabilities	12,236,000,000	$ 5,433,000,000
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities
Trading Assets	2,600,000,000
Total assets	2,700,000,000
Other Liabilities	116,000,000
Buildings and building improvements
Variable Interest Entities
Buildings and Improvements, Gross	456,000,000
Max
Loss Contingency [Abstract]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	210,000,000
Min
Loss Contingency [Abstract]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	$ 0