INVESTMENTS - Investment Exposures Individually Exceeded 10% of Shareholders' Equity (Details) - Japan National Government - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Summary of Investment Holdings [Line Items]
Credit Rating	[1]	A	A
Amortized Cost	[1]	$ 47,637	$ 42,931
Fair Value	[1]	$ 55,444	$ 51,345

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