Mortgage Loans Held for Portfolio (Other Delinquency Statistics) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	$ 3	$ 5
Residential Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Past Due 90 Days or More and Still Accruing Interest	8	7
Financing Receivable, Non-Accrual	$ 62	$ 49
Residential Portfolio Segment | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Percent Past Due	0.00%	0.00%
Loans Insured or Guaranteed by US Government Authorities [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	$ 1	$ 1
Loans Insured or Guaranteed by US Government Authorities [Member] | Residential Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Past Due 90 Days or More and Still Accruing Interest	8	7
Financing Receivable, Non-Accrual	$ 0	$ 0
Loans Insured or Guaranteed by US Government Authorities [Member] | Residential Portfolio Segment | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Percent Past Due	2.00%	2.00%
Conventional Mortgage Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	$ 2	$ 4
Conventional Mortgage Loans [Member] | Residential Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Past Due 90 Days or More and Still Accruing Interest	0	0
Financing Receivable, Non-Accrual	$ 62	$ 49
Conventional Mortgage Loans [Member] | Residential Portfolio Segment | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Percent Past Due	0.00%	0.00%