BUSINESS SEGMENT INFORMATION AND SELECTED FOREIGN CURRENCY TRANSLATION ITEMS - Information on Transfers of Funds from Aflac Japan (Detail) $ in Millions, ¥ in Billions	12 Months Ended
	Dec. 31, 2025 USD ($)	Dec. 31, 2025 JPY (¥)	Dec. 31, 2024 USD ($)	Dec. 31, 2024 JPY (¥)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 JPY (¥)
Segment Reporting [Abstract]
Management fees	$ 73		$ 69		$ 67
Profit remittances	2,681	¥ 396.7	2,865	¥ 441.6	2,623	¥ 374.7
Total transfers from Aflac Japan	$ 2,754		$ 2,934		$ 2,690