Guarantee Arrangements and Pledged Assets and Repurchase Agreements - Offsetting of Resale and Repurchase Agreements and Securities Borrowing and Lending Agreements (Details) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Securities purchased under agreements to resell, Gross Amounts Recognized		$ 7,190	$ 41,382
Securities purchased under agreements to resell, Gross Amounts Offset in the Balance Sheet	[1]	3,430	5,636
Securities purchased under agreements to resell, Net amounts Prsented in the Balance Sheet		3,760	35,746
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Financial Instruments	[2]	3,687	35,746
Securities purchased under agreements to resell, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Receive / Pledged		10	0
Securities purchased under agreements to resell, Net amount	[3]	63	0
Securities sold under repurchase agreements, Gross Amounts Recognized		5,147	7,401
Securities sold under repurchase agreements, Gross Amounts Offset in the Balance Sheet	[1]	3,430	5,636
Securities sold under repurchase agreements, Net Amounts Presented in the Balance Sheet		1,717	1,765
Securities sold under repurchase agreements, Gross Amounts Not Offset in the Balance sheet, Financial Instruments	[2]	1,654	1,762
Securities sold under repurchase agreements, Gross Amounts Not Offset in the Balance Sheet, Cash Collateral Received / Pledged		62	0
Securities sold under repurchase agreements, Net amount	[3]	$ 1	$ 3

[1] Represents recognized amount of resale and repurchase agreements with counterparties subject to legally enforceable netting agreements that meet the applicable netting criteria as permitted by generally accepted accounting principles.

[2] Represents securities received or pledged to cover financing transaction exposures.

[3] Represents the amount of our exposure that is not collateralized / covered by pledged collateral.