Future Policy Benefits (Undiscounted and Discounted) (Details) - Other Segments - USD ($) $ in Millions	Mar. 31, 2023	Mar. 31, 2022
Americas [Member] | Life Insurance Product Line [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	$ 82,288	$ 93,268
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	181,123	181,789
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	80,478	91,772
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	172,081	172,097
Americas [Member] | Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	1,975	686
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	9,214	7,360
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	5,408	4,648
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	3,112	972
CANADA | Life Insurance Product Line [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	21,317	24,355
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	56,223	60,162
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	21,289	24,421
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	53,244	56,648
CANADA | Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	3,149	3,843
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	4,602	5,387
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	3,062	3,760
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	4,738	5,506
EMEA [Member] | Life Insurance Product Line [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	13,611	16,254
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	24,150	24,939
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	12,889	15,377
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	24,591	25,517
EMEA [Member] | Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	37,636	41,655
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	66,775	59,907
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	39,070	43,738
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	64,424	56,874
Asia Pacific [Member] | Life Insurance Product Line [Member]
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	37,986	38,094
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	88,496	82,052
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	32,313	32,473
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	92,305	84,355
Asia Pacific [Member] | Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	2,478	2,840
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	10,144	9,175
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	7,472	7,107
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	$ 2,977	$ 3,280