Goodwill, Other intangible assets, and Value of business acquired (Estimated Amortization Expense Over Next Five Years) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Finite-Lived Intangible Assets [Line Items]
2023, Other intangible assets	$ 354
2024, Other intangible assets	315
2025, Other intangible assets	288
2026, Other intangible assets	265
2027, Other intangible assets	253
Total, Other intangible assets	1,475
Chubb Acquired Purchased Intangible Assets
Finite-Lived Intangible Assets [Line Items]
2023, Other intangible assets	312
2024, Other intangible assets	287
2025, Other intangible assets	269
2026, Other intangible assets	250
2027, Other intangible assets	240
Total, Other intangible assets	1,358
Use Rights [Member] | Huatai Group [Member]
Finite-Lived Intangible Assets [Line Items]
2023, Other intangible assets	12	[1]
2024, Other intangible assets	12	[1]
2025, Other intangible assets	12	[1]
2026, Other intangible assets	12	[1]
2027, Other intangible assets	13	[1]
Total, Other intangible assets	61	[1]
Unearned Premium Reserves Intangible Asset | Huatai Group [Member]
Finite-Lived Intangible Assets [Line Items]
2023, Other intangible assets	30	[2]
2024, Other intangible assets	16	[2]
2025, Other intangible assets	7	[2]
2026, Other intangible assets	3	[2]
2027, Other intangible assets	0	[2]
Total, Other intangible assets	$ 56	[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.