INCOME TAXES - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Japan Tax Rate	28.00%	28.00%	28.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax Asset (Liability)	$ 208	$ 174	$ 452
U.S. federal statutory corporate income tax rate	21.00%	21.00%	21.00%
Non-life operating loss carryforwards, limitations	only 35% of non-life operating losses can be offset against life insurance taxable income each year
Unrecognized tax benefit, deductibility highly certain, timing uncertain	$ 0	$ 0
Unrecognized tax benefits, interest and penalties expense	0	0	$ 0
Unrecognized tax benefits, accrued interest and penalties	0	$ 0
Non-life
Income Taxes [Line Items]
Non-life operating loss carryforwards	26
Life
Income Taxes [Line Items]
Non-life operating loss carryforwards	92
Capital Loss Carryforward
Income Taxes [Line Items]
Tax credit carryforward, amount	0
Foreign Tax Credit
Income Taxes [Line Items]
Tax credit carryforward, amount	$ 314