Intangible Assets (Roll-forward of Goodwill by Business Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Balance at beginning of period	$ 15,400	$ 15,296
Foreign exchange revaluation and other	(187)	60
Balance at end of period	15,213	15,400
North America Commercial P&C Insurance
Goodwill [Roll Forward]
Balance at beginning of period	6,972	6,955
Foreign exchange revaluation and other	0	17
Balance at end of period	6,972	6,972
North America Personal P&C Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	2,240	2,234
Foreign exchange revaluation and other	0	6
Balance at end of period	2,240	2,240
North America Agricultural Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	134	134
Foreign exchange revaluation and other	0	0
Balance at end of period	134	134
Overseas General Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	4,836	4,785
Foreign exchange revaluation and other	(183)	35
Balance at end of period	4,653	4,836
Global Reinsurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	371	371
Foreign exchange revaluation and other	0	0
Balance at end of period	371	371
Life Insurance [Member]
Goodwill [Roll Forward]
Balance at beginning of period	847	817
Foreign exchange revaluation and other	(4)	2
Balance at end of period	$ 843	847
Banchile Seguros de Vida [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		44
Banchile Seguros de Vida [Member] | North America Commercial P&C Insurance
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0
Banchile Seguros de Vida [Member] | North America Agricultural Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0
Banchile Seguros de Vida [Member] | Overseas General Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		16
Banchile Seguros de Vida [Member] | Global Reinsurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0
Banchile Seguros de Vida [Member] | Life Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		28
Banchile Seguros de Vida [Member] | North America Personal P&C Insurance [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		$ 0