Pledged Assets (Assets Pledged as Collateral) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Offsetting Assets and Liabilities [Line Items]
Accrued interest on pledged securities	$ 128	$ 120
Restricted cash	1,316	527
Total Fair Value of Securities Pledged and Accrued Interest	39,217
Total Fair Value Of Agency Securities Pledged And Accrued Interest		50,910
Security Owned and Pledged as Collateral, Fair Value	37,426	48,496
Retained Interests in Consolidated VIE's Pledged as Collateral Under Repurchase Agreements	49	81
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	35,765	46,943
Derivative Agreements and Other
Offsetting Assets and Liabilities [Line Items]
Total Fair Value of Securities Pledged and Accrued Interest	1,308	1,461
Security Owned and Pledged as Collateral, Fair Value	203	739
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Accrued interest on pledged securities	127	117
Total Fair Value of Securities Pledged and Accrued Interest	37,764
Total Fair Value Of Agency Securities Pledged And Accrued Interest		49,240
Variable Interest Entity, Primary Beneficiary [Member]
Offsetting Assets and Liabilities [Line Items]
Accrued interest on pledged securities	1	1
Total Fair Value of Securities Pledged and Accrued Interest	145
Total Fair Value Of Agency Securities Pledged And Accrued Interest		209
Security Owned and Pledged as Collateral, Fair Value	144	208
Includes Sold But Not Yet Settled Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	36,112	47,890
Credit Risk Transfer Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	703	510
Credit Risk Transfer Securities [Member] | Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	703	510
Non-Agency [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	605	571
Non-Agency [Member] | Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	605	571
US Treasury Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	353	1,292
US Treasury Securities [Member] | Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	353	1,084
US Treasury Securities [Member] | Derivative Agreements and Other
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	0	208
Derivative Agreements and Other
Offsetting Assets and Liabilities [Line Items]
Accrued interest on pledged securities	0	2
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted cash	211	15
Excluding Cash Received [Member]
Offsetting Assets and Liabilities [Line Items]
Restricted cash	1,316	527
Derivative Agreements and Other
Offsetting Assets and Liabilities [Line Items]
Restricted cash	$ 1,105	$ 512