Pledged Assets (Securities Pledged as Collateral) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 92,210	$ 87,420
Agency Securities Pledged As Collateral Amortized Cost	93,224	87,440
Agency Securities Pledged As Collateral Accrued Interest	496	430
Maturity Less than 30 Days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	86,421	83,600
Agency Securities Pledged As Collateral Amortized Cost	87,251	83,502
Agency Securities Pledged As Collateral Accrued Interest	473	415
Maturity 31 To 59 Days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	1,519	3,324
Agency Securities Pledged As Collateral Amortized Cost	1,591	3,435
Agency Securities Pledged As Collateral Accrued Interest	6	13
Maturity 60 To 90 Days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	4,270	496
Agency Securities Pledged As Collateral Amortized Cost	4,382	503
Agency Securities Pledged As Collateral Accrued Interest	17	2
Maturity over 90 days [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	0	0
Agency Securities Pledged As Collateral Amortized Cost	0	0
Agency Securities Pledged As Collateral Accrued Interest	0	0
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	80,952	74,213
Credit Risk Transfer Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	525	558
Credit Risk Transfer Securities [Member] \| Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	525	558
US Treasury Securities [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	11,304	13,076
US Treasury Securities [Member] \| Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	10,725	12,636
Non-Agency [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	8	13
Non-Agency [Member] \| Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 8	$ 13