Goodwill, Other intangible assets, and Value of business acquired (Estimated Amortization Expense Over Next Five Years) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Finite-Lived Intangible Assets [Line Items]
2025, Other intangible assets	$ 326
2026, Other intangible assets	298
2027, Other intangible assets	274
2028, Other intangible assets	260
2029, Other intangible assets	228
Total, Other intangible assets	1,386
Chubb Acquired Purchased Intangible Assets
Finite-Lived Intangible Assets [Line Items]
2025, Other intangible assets	298
2026, Other intangible assets	279
2027, Other intangible assets	259
2028, Other intangible assets	247
2029, Other intangible assets	215
Total, Other intangible assets	1,298
Use Rights [Member] | Huatai Group [Member]
Finite-Lived Intangible Assets [Line Items]
2025, Other intangible assets	12	[1]
2026, Other intangible assets	12	[1]
2027, Other intangible assets	12	[1]
2028, Other intangible assets	13	[1]
2029, Other intangible assets	13	[1]
Total, Other intangible assets	62	[1]
Unearned Premium Reserves Intangible Asset | Huatai Group [Member]
Finite-Lived Intangible Assets [Line Items]
2025, Other intangible assets	16	[2]
2026, Other intangible assets	7	[2]
2027, Other intangible assets	3	[2]
2028, Other intangible assets	0	[2]
2029, Other intangible assets	0	[2]
Total, Other intangible assets	$ 26	[2]

[1] Recognized in Other (income) expense in the Consolidated statements of operations.

[2] Recognized in Policy acquisition costs in the Consolidated statements of operations.