Investments - Reconciliation of Available-for-Sale Securities from Cost Basis to Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 88,978	$ 88,231
Gross Unrealized Gains	754	1,054
Gross Unrealized Losses	7,786	6,966
Allowance for Credit Losses	46	19	$ 21	$ 19
Fair Value	81,900	82,300
Corporate bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	67,991	68,811
Gross Unrealized Gains	560	820
Gross Unrealized Losses	6,704	5,757
Allowance for Credit Losses	14	8	9	17
Fair Value	61,833	63,866
U.S. government bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	427	414
Gross Unrealized Gains	3	7
Gross Unrealized Losses	40	28
Allowance for Credit Losses	0	0
Fair Value	390	393
State and municipal bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	2,391	2,675
Gross Unrealized Gains	27	97
Gross Unrealized Losses	270	230
Allowance for Credit Losses	0	0
Fair Value	2,148	2,542
Foreign government bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	277	309
Gross Unrealized Gains	12	15
Gross Unrealized Losses	56	46
Allowance for Credit Losses	0	0
Fair Value	233	278
RMBS
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,849	1,719
Gross Unrealized Gains	23	27
Gross Unrealized Losses	162	138
Allowance for Credit Losses	7	6	7	1
Fair Value	1,703	1,602
CMBS
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,713	1,520
Gross Unrealized Gains	5	5
Gross Unrealized Losses	135	181
Allowance for Credit Losses	0	0
Fair Value	1,583	1,344
ABS
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	14,103	12,556
Gross Unrealized Gains	99	62
Gross Unrealized Losses	409	571
Allowance for Credit Losses	24	4	$ 4	$ 0
Fair Value	13,769	12,043
Hybrid and redeemable preferred securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	227	227
Gross Unrealized Gains	25	21
Gross Unrealized Losses	10	15
Allowance for Credit Losses	1	1
Fair Value	$ 241	$ 232

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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