Investments - Reconciliation of Available-for-Sale Securities from Cost Basis to Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 94,635	$ 92,842
Gross Unrealized Gains	798	1,118
Gross Unrealized Losses	6,993	6,264
Allowance for Credit Losses	111	110	$ 73	$ 46
Fair Value	88,329	87,586
Corporate bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	68,566	68,479
Gross Unrealized Gains	599	837
Gross Unrealized Losses	6,195	5,540
Allowance for Credit Losses	38	53	23	14
Fair Value	62,932	63,723
U.S. government bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	950	890
Gross Unrealized Gains	5	9
Gross Unrealized Losses	36	32
Allowance for Credit Losses	0	0
Fair Value	919	867
State and municipal bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	2,151	2,161
Gross Unrealized Gains	27	35
Gross Unrealized Losses	235	231
Allowance for Credit Losses	0	0
Fair Value	1,943	1,965
Foreign government bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	240	256
Gross Unrealized Gains	15	17
Gross Unrealized Losses	53	50
Allowance for Credit Losses	0	0
Fair Value	202	223
RMBS
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,995	2,034
Gross Unrealized Gains	39	45
Gross Unrealized Losses	118	108
Allowance for Credit Losses	6	6	6	7
Fair Value	1,910	1,965
CMBS
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	2,682	2,493
Gross Unrealized Gains	9	17
Gross Unrealized Losses	100	87
Allowance for Credit Losses	0	0
Fair Value	2,591	2,423
ABS
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	17,830	16,301
Gross Unrealized Gains	93	137
Gross Unrealized Losses	249	210
Allowance for Credit Losses	66	50	$ 43	$ 24
Fair Value	17,608	16,178
Hybrid and redeemable preferred securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	221	228
Gross Unrealized Gains	11	21
Gross Unrealized Losses	7	6
Allowance for Credit Losses	1	1
Fair Value	$ 224	$ 242

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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