INCOME TAXES - Income Tax Effects of Temporary Differences that Gave Rise to Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred income tax liabilities:
Deferred policy acquisition costs	$ 3,492	$ 3,404
Unrealized gains and other basis differences on investments	4,485	1,307
Premiums receivable	152	149
Policy benefit reserves	3,442	3,828
Total deferred income tax liabilities	11,571	8,688
Deferred income tax assets:
Unfunded retirement benefits	8	8
Other accrued expenses	36	40
Policy and contract claims	781	775
Foreign currency loss on Aflac Japan	16	38
Deferred compensation	162	163
Capital loss carryforwards	34	5
Depreciation	164	119
Anticipatory foreign tax credit	5,487	4,040
Deferred foreign tax credit	605	591
Other	204	150
Total deferred income tax assets before valuation allowance	7,497	5,929
Valuation allowance	(1,340)	(738)
Total deferred income tax assets after valuation allowance	6,157	5,191
Net deferred income tax liability	5,414	3,497
Current income tax asset	(44)
Current income tax liability		523
Total income tax liability	$ 5,370	$ 4,020