Investments (AFS Major Security Types) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	$ 314	$ 211
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(17)	(28)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	28,478	27,336
Debt Securities, Available-for-Sale, Excluding Accrued Interest	28,775	27,519
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss	89	89
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	4	14
Debt Securities, Available-for-Sale, Excluding Accrued Interest	4	14
US Government-sponsored Enterprises Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	28	30
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	276	280
Debt Securities, Available-for-Sale, Excluding Accrued Interest	304	310
State or local housing agency obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2	2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(2)	(1)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	454	369
Debt Securities, Available-for-Sale, Excluding Accrued Interest	454	370
Other Debt Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	18	18
Debt Securities, Available-for-Sale, Excluding Accrued Interest	19	19
Non-mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	31	33
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(2)	(1)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	752	681
Debt Securities, Available-for-Sale, Excluding Accrued Interest	781	713
Mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	283	178
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(15)	(27)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	27,726	26,655
Debt Securities, Available-for-Sale, Excluding Accrued Interest	27,994	26,806
Single Family [Member] \| U.S. obligations MBS [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	48	25
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	(1)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	6,759	5,683
Debt Securities, Available-for-Sale, Excluding Accrued Interest	6,807	5,707
Single Family [Member] \| Mortgage-backed securities, GSE [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	(1)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	199	217
Debt Securities, Available-for-Sale, Excluding Accrued Interest	200	217
Multifamily [Member] \| Mortgage-backed securities, GSE [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	234	152
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(15)	(25)
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss	20,768	20,755
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 20,987	$ 20,882

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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