Schedule II - Aflac Incorporated (Parent Only) - Condensed Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net earnings	$ 4,325	$ 4,778	$ 3,304
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period	(889)	510	252
Unrealized gains (losses) on derivatives during period	5	(1)	(12)
Pension liability adjustment during period	148	(7)	(85)
Total other comprehensive income (loss) before income taxes	(1,696)	1,722	6,007
Income tax expense (benefit) related to items of other comprehensive income (loss)	(155)	251	1,543
Other comprehensive income (loss), net of tax	(1,541)	1,471	4,464
Total comprehensive income (loss)	2,784	6,249	7,768
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net earnings	4,325	4,778	3,304
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period	(889)	510	252
Unrealized gains (losses) on fixed maturity securities during period	(960)	1,220	5,852
Unrealized gains (losses) on derivatives during period	5	(1)	(12)
Pension liability adjustment during period	148	(7)	(85)
Total other comprehensive income (loss) before income taxes	(1,696)	1,722	6,007
Income tax expense (benefit) related to items of other comprehensive income (loss)	(155)	251	1,543
Other comprehensive income (loss), net of tax	(1,541)	1,471	4,464
Total comprehensive income (loss)	$ 2,784	$ 6,249	$ 7,768