Fair Value - Level 3 Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Available-for-Sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 427	$ 514
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(19)	(37)
Net transfers	0	0
Total gains (losses) realized & unrealized	(3)	10
Ending Balance	405	487
Mortgage Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	399	477
Purchases	0	0
Sales	0	(4)
Issuances	0	0
Settlements	(16)	(17)
Net transfers	(2)	13
Total gains (losses) realized & unrealized	7	1
Ending Balance	388	470
Net Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	39	77
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	1	4
Net transfers	0	0
Total gains (losses) realized & unrealized	(5)	(12)
Ending Balance	35	69
Long-term Debt
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(353)	(385)
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	4	4
Net transfers	0	0
Total gains (losses) realized & unrealized	(15)	(6)
Ending Balance	(364)	(387)
Mortgage-related securities | Trading Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	28	26
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Net transfers	(3)	3
Total gains (losses) realized & unrealized	1	(1)
Ending Balance	$ 26	$ 28