Commitments and Contingencies (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Loss Contingencies [Line Items]
Obligation with Joint and Several Liability Arrangement, Amount Outstanding	$ 1,015,700	$ 977,400
Other liabilities	259	73
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	18,463
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	128
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	18,591	18,263
Financial Standby Letter of Credit [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	231
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	1,071
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	1,302	1,249
Loan Origination Commitments [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	38
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	0
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	38	151
Commitments to Issue Discount Notes [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	857
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	0
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	857	3,060
Commitments to Issue Bonds
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	4,545
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	0
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	4,545	1,000
Mortgages [Member] | Forward Contracts [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	328
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	0
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	328	106
standby letters of credit issuance commitments [Domain]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 0	$ 0