Accumulated other comprehensive income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 443,164
Other comprehensive income	99	$ 905	$ (275)
Reclassifications into net earnings	117	95	47
Ending Balance	506,199	443,164
Unrealized appreciation of fixed maturity securities, net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	536	481	370
Other comprehensive income	(123)	78	160
Reclassifications into net earnings	(44)	(23)	(49)
Ending Balance	369	536	481
Foreign currency translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3,082)	(4,346)	(4,603)
Other comprehensive income	(1,021)	1,264	257
Reclassifications into net earnings	11
Ending Balance	(4,092)	(3,082)	(4,346)
Defined benefit pension plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,645)	(1,369)	(816)
Other comprehensive income	1,163	(385)	(644)
Reclassifications into net earnings	135	109	91
Ending Balance	(347)	(1,645)	(1,369)
Other AOCI transactions [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(52)	(9)	34
Other comprehensive income	80	(52)	(48)
Reclassifications into net earnings	15	9	5
Ending Balance	43	(52)	(9)
Accumulated other comprehensive income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(4,243)	(5,243)	(5,015)
Ending Balance	$ (4,027)	$ (4,243)	$ (5,243)