Investments (AFS Major Security Types) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	$ 211	$ 84
Gross Unrealized Losses	(28)	(111)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	27,336	25,358
Available-for-sale securities (amortized cost of $27,336 and $25,358)	27,519	25,331
U.S. Obligations [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	14	102
Available-for-sale securities (amortized cost of $27,336 and $25,358)	14	102
US Government-sponsored Enterprises Debt Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	30	24
Gross Unrealized Losses	0	0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	280	285
Available-for-sale securities (amortized cost of $27,336 and $25,358)	310	309
State or Local Housing Agency Obligations [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	2	1
Gross Unrealized Losses	(1)	(6)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	369	504
Available-for-sale securities (amortized cost of $27,336 and $25,358)	370	499
Other [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	1	1
Gross Unrealized Losses	0	0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	18	41
Available-for-sale securities (amortized cost of $27,336 and $25,358)	19	42
Non-Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	33	26
Gross Unrealized Losses	(1)	(6)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	681	932
Available-for-sale securities (amortized cost of $27,336 and $25,358)	713	952
U.S. Obligations MBS [Member] | Single Family [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	25	13
Gross Unrealized Losses	(1)	(5)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	5,683	5,192
Available-for-sale securities (amortized cost of $27,336 and $25,358)	5,707	5,200
GSE MBS [Member] | Single Family [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(1)	(2)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	217	197
Available-for-sale securities (amortized cost of $27,336 and $25,358)	217	195
GSE MBS [Member] | Multifamily [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	152	45
Gross Unrealized Losses	(25)	(98)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	20,755	19,037
Available-for-sale securities (amortized cost of $27,336 and $25,358)	20,882	18,984
Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Gross Unrealized Gains	178	58
Gross Unrealized Losses	(27)	(105)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	26,655	24,426
Available-for-sale securities (amortized cost of $27,336 and $25,358)	$ 26,806	$ 24,379