Future Policy Benefits (Undiscounted and Discounted) (Details) - Other Segments - USD ($) $ in Millions	Sep. 30, 2026	Sep. 30, 2025
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	$ 79,596	$ 88,432
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	199,720	203,397
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	77,400	87,447
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	193,711	194,959
Americas [Member] \| Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	3,009	1,641
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	27,137	22,213
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	12,881	10,902
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	5,101	2,554
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	20,803	22,317
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	57,085	57,445
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	20,459	22,132
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	56,723	56,351
CANADA \| Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	3,184	3,733
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	16,577	17,625
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	7,074	7,996
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	4,969	5,676
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	17,634	16,513
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	34,293	30,886
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	17,075	16,284
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	33,936	30,092
EMEA [Member] \| Insurance, Other
Liability for Future Policy Benefit, Activity [Line Items]
Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance	81,563	77,444
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	183,642	170,551
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	85,900	85,239
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	176,568	157,690
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	50,607	46,387
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	131,768	109,528
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	43,014	39,452
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	137,965	113,661
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	4,723	3,471
Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance	44,136	30,139
Liability For Future Policy Benefit Expected Future Policy Benefit Discounted Before Reinsurance	18,260	14,068
Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance	$ 7,530	$ 5,235

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Amount, before effect of reinsurance, of discounted balance for expected future gross premium component of liability for future policy benefit.

+ References

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Amount, before effect of reinsurance, of undiscounted balance for expected future gross premium component of liability for future policy benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147480081/944-40-50-6

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Amount, before effect of reinsurance, of undiscounted balance for expected future policy benefit and expense component of liability for future policy benefit.

+ References

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