Investments - Unrealized Loss (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	$ 34,419	$ 20,644
Gross Unrealized Losses	4,169	2,286
Additional impairment losses	0
AAA
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	3,408	1,376
Gross Unrealized Losses	446	243
AA
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	6,102	3,827
Gross Unrealized Losses	1,062	623
A
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	8,304	5,025
Gross Unrealized Losses	843	440
BBB
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	12,137	7,758
Gross Unrealized Losses	1,181	639
U.S. Government, Government agencies and Government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	3,200	1,980
Gross Unrealized Losses	469	267
Non-investment grade
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	1,268	678
Gross Unrealized Losses	$ 168	$ 74

Amount of additional other-than-temporary impairment losses on investments in available-for-sale securities.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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