INCOME TAXES - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Sep. 30, 2020	Jan. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Japan Tax Rate			28.00%	28.00%	28.00%
U.S. federal statutory corporate income tax rate		21.00%	21.00%	21.00%	21.00%	35.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax Asset (Liability)	$ (1,400)
Deferred Tax Assets, Valuation Allowance			$ 0	$ 1,340
Non-life operating loss carryforwards, limitations			only 35% of non-life operating losses can be offset against life insurance taxable income each year
Operating Loss Carryforwards			$ 298
Unrecognized tax benefit, deductibility highly certain, timing uncertain			15	15
Unrecognized tax benefits, permanent uncertainties			4
Unrecognized tax benefits, interest and penalties expense			1	1	$ 1
Unrecognized tax benefits, accrued interest and penalties			3	$ 2
Capital Loss Carryforward
Income Taxes [Line Items]
Tax Credit Carryforward, Amount			55
Foreign Tax Credit
Income Taxes [Line Items]
Tax Credit Carryforward, Amount			$ 22