BUSINESS SEGMENT AND FOREIGN INFORMATION - Information on Transfers of Funds from Aflac Japan (Detail) $ in Millions, ¥ in Billions	12 Months Ended
Dec. 31, 2021 USD ($)	Dec. 31, 2021 JPY (¥)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 JPY (¥)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 JPY (¥)
Segment Reporting [Abstract]
Management fees	$ 59		$ 71		$ 75
Allocated expenses	0		0		4
Profit remittances	2,138	¥ 236.7	1,215	¥ 129.8	2,070	¥ 225.2
Total transfers from Aflac Japan	$ 2,197		$ 1,286		$ 2,149

Amount of foreign earnings repatriated from subsidiaries outside the country of domicile.

No definition available.

Name:	us-gaap_ForeignEarningsRepatriated
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration