Commitments Contingencies and Guarantees (Maximum Potential Obligation) (Details) $ in Millions	Dec. 31, 2019 USD ($)
Commitment Period Two Thousand Thirty Five [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 2,654
Commitment Period Two Thousand Thirty Six [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	3,408
Commitment Period Two Thousand Thirty Seven [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	5,750
Commitment Period Two Thousand Thirty Eight [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	1,800
Commitment Period Two Thousand Thirty Nine [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 5,750