Investments - Schedule of Amortized Cost, Gross Unrealized Gains (Losses) and Fair Value for Fixed Income Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Schedule of Available for Sale Securities
Amortized cost, net	$ 53,616	$ 49,649
Gross unrealized gains	361	650
Gross unrealized losses	(1,230)	(1,434)
Fixed income securities, at fair value	52,747	48,865
U.S. government and agencies
Schedule of Available for Sale Securities
Amortized cost, net	11,423	8,624
Gross unrealized gains	15	114
Gross unrealized losses	(330)	(119)
Fixed income securities, at fair value	11,108	8,619
Municipal
Schedule of Available for Sale Securities
Amortized cost, net	8,985	6,049
Gross unrealized gains	33	109
Gross unrealized losses	(176)	(152)
Fixed income securities, at fair value	8,842	6,006
Corporate
Schedule of Available for Sale Securities
Amortized cost, net	30,630	31,951
Gross unrealized gains	272	397
Gross unrealized losses	(710)	(1,143)
Fixed income securities, at fair value	30,192	31,205
Foreign government
Schedule of Available for Sale Securities
Amortized cost, net	1,352	1,286
Gross unrealized gains	22	17
Gross unrealized losses	(10)	(13)
Fixed income securities, at fair value	1,364	1,290
ABS
Schedule of Available for Sale Securities
Amortized cost, net	1,226	1,739
Gross unrealized gains	19	13
Gross unrealized losses	(4)	(7)
Fixed income securities, at fair value	$ 1,241	$ 1,745

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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Amount, before tax, of unrealized loss 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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Amortized cost excluding accrued interest, after allowance for credit loss, of 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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