INVESTMENTS - Investment Exposures Individually Exceeded Ten Percent of Shareholders' Equity (Detail) - Japan National Government - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Summary of Investment Holdings [Line Items]
Credit Rating		A	A
Amortized Cost	[1]	$ 48,399	$ 42,931
Fair Value	[1]	$ 56,532	$ 51,345

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