Market Risk Benefits (Instrument Specific Credit Risk) (Details) - USD ($) $ in Millions		Mar. 31, 2024	Mar. 31, 2023
Market Risk Benefit [Line Items]
Market Risk Benefit, after Increase (Decrease) from Instrument-Specific Credit Risk		$ (214)	$ (259)
Market Risk Benefit, Asset, Amount	[1]	14	2
Market Risk Benefit, Liability, Amount		228	261
Insurance, Other | Americas [Member] | Other Segments
Market Risk Benefit [Line Items]
Market Risk Benefit, after Increase (Decrease) from Instrument-Specific Credit Risk		(214)	(259)
Market Risk Benefit, Asset, Amount	[1]	14	2
Market Risk Benefit, Liability, Amount		$ 228	$ 261

[1] Included in Other assets