INVESTMENTS - Investment Exposures Individually Exceeded 10% of Shareholders' Equity (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2025	Dec. 31, 2024
Investments [Abstract]
Credit Rating	[1]	A+	A+
Amortized Cost	[1]	$ 34,849	$ 33,822
Fair Value	[1]	$ 31,596	$ 32,844
Investment, Type [Extensible Enumeration]		Japan National Government [Member]	Japan National Government [Member]

[1] Japan Government Bonds (JGBs) or JGB-backed securities