Investments - Unrealized Loss (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	$ 23,987	$ 27,288
Gross Unrealized Losses	2,738	3,039
Additional impairment losses	0
AAA
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	1,578	1,800
Gross Unrealized Losses	280	282
AA
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	4,224	4,247
Gross Unrealized Losses	735	730
A
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	5,891	6,330
Gross Unrealized Losses	522	582
BBB
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	9,531	11,548
Gross Unrealized Losses	787	980
U.S. Government, Government agencies and Government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	2,086	2,567
Gross Unrealized Losses	322	373
Non-investment grade
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	677	796
Gross Unrealized Losses	$ 92	$ 92

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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