Goodwill, Other intangible assets, and Value of business acquired (Roll-forward of Goodwill by Business Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024		Dec. 31, 2023
Goodwill [Roll Forward]
Balance at beginning of period	$ 19,686		$ 16,228
Goodwill, Purchase Accounting Adjustments	65		(2)
Foreign exchange revaluation and other	(428)		66
Balance at end of period	19,579	[1]	19,686
goodwill attributable to noncontrolling interests	499
North America Commercial P&C Insurance
Goodwill [Roll Forward]
Balance at beginning of period	6,946		6,945
Goodwill, Purchase Accounting Adjustments	0		0
Foreign exchange revaluation and other	(34)		1
Balance at end of period	7,168	[1]	6,946
North America Personal P&C Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	2,231		2,230
Goodwill, Purchase Accounting Adjustments	0		0
Foreign exchange revaluation and other	(13)		1
Balance at end of period	2,218	[1]	2,231
North America Agricultural Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	134		134
Goodwill, Purchase Accounting Adjustments	0		0
Foreign exchange revaluation and other	0		0
Balance at end of period	134	[1]	134
Overseas General Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	5,262		4,605
Goodwill, Purchase Accounting Adjustments	0		8
Foreign exchange revaluation and other	(215)		87
Balance at end of period	5,047	[1]	5,262
Global Reinsurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	371		371
Goodwill, Purchase Accounting Adjustments	0		0
Foreign exchange revaluation and other	0		0
Balance at end of period	371	[1]	371
Life Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	4,742		1,943
Goodwill, Purchase Accounting Adjustments	65		(10)
Foreign exchange revaluation and other	(166)		(23)
Balance at end of period	4,641	[1]	4,742
Huatai Group [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period			3,394
Huatai Group [Member] | North America Commercial P&C Insurance
Goodwill [Roll Forward]
Goodwill, Acquired During Period			0
Huatai Group [Member] | North America Personal P&C Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period			0
Huatai Group [Member] | North America Agricultural Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period			0
Huatai Group [Member] | Overseas General Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period			562
Huatai Group [Member] | Global Reinsurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period			0
Huatai Group [Member] | Life Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period			$ 2,832
Healthy Paws
Goodwill [Roll Forward]
Goodwill, Acquired During Period	256
Healthy Paws | North America Commercial P&C Insurance
Goodwill [Roll Forward]
Goodwill, Acquired During Period	256
Healthy Paws | North America Personal P&C Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
Healthy Paws | North America Agricultural Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
Healthy Paws | Overseas General Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
Healthy Paws | Global Reinsurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	0
Healthy Paws | Life Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period	$ 0

[1] Includes $499 million attributable to noncontrolling interests