Schedule II - Aflac Incorporated (Parent Only) - Summary of Notes Payable and Lease Obligations (Detail 1) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Condensed Financial Statements, Captions [Line Items]
Operating lease obligations	$ 91	$ 118
Notes payable and lease obligations	7,498	7,364
1.125% senior notes due March 2026
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	399	398
2.875% senior notes due October 2026
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	299	299
3.60% senior notes due April 2030
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	994	993
6.90% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	221	221
6.45% senior notes due August 2040
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	255	254
4.00% senior noted due October 2046
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	394	394
4.750% senior notes due January 2049
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	542	542
.300% senior notes due September 2025
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	79	87
.932% senior notes due January 2027
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	378	422
1.048% senior notes due March 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	81	0
1.075% senior notes due September 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	211	234
.500% senior notes due December 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	79	88
.550% senior notes due March 2030
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	84	93
1.159% senior notes due October 2030
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	184	206
1.412% senior notes due March 2031
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	176	0
.633% senior notes due April 2031
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	189	211
.843% senior notes due December 2031
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	58	65
.750% senior notes due March 2032
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	130	145
1.320% senior notes due December 2032
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	133	148
.844% senior notes due April 2033
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	76	84
1.488% senior notes due October 2033
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	95	106
1.682% senior notes due March 2034
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	48	0
1.600% senior notes due March 2034
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	115	0
.934% senior notes due December 2034
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	62	69
.830% senior notes due March 2035
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	66	74
1.740% senior notes due March 2036
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	94	0
1.039% senior notes due April 2036
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	63	70
1.594% senior notes due September 2037
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	41	45
1.750% senior notes due October 2038
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	56	62
1.920% senior notes due March 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	103	0
1.122% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	39	44
1.264% senior notes due April 2041
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	63	70
2.160% senior notes due March 2044
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	35	0
2.108% subordinated notes due October 2047
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	375	419
1.560% senior notes due April 2051
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	125	140
2.144% senior notes due September 2052
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	75	84
2.400% senior notes due March 2054
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	122	0
Yen-denominated loan variable interest rate due August 2027
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	74	82
Yen-denominated loan variable interest rate due August 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	160	178
Yen-denominated loan variable interest rate due August 2032
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	441	492
Parent Company
Condensed Financial Statements, Captions [Line Items]
Operating lease obligations	5	0
Notes payable and lease obligations	7,219	6,819
Parent Company | 1.125% senior notes due March 2026
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	399	398
Parent Company | 2.875% senior notes due October 2026
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	299	299
Parent Company | 3.60% senior notes due April 2030
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	994	993
Parent Company | 6.90% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	221	221
Parent Company | 6.45% senior notes due August 2040
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	255	254
Parent Company | 4.00% senior noted due October 2046
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	394	394
Parent Company | 4.750% senior notes due January 2049
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	542	542
Parent Company | .300% senior notes due September 2025
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	79	87
Parent Company | .932% senior notes due January 2027
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	378	422
Parent Company | 1.048% senior notes due March 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	81	0
Parent Company | 1.075% senior notes due September 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	211	234
Parent Company | .500% senior notes due December 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	79	88
Parent Company | .550% senior notes due March 2030
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	84	93
Parent Company | 1.159% senior notes due October 2030
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	184	206
Parent Company | 1.412% senior notes due March 2031
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	176	0
Parent Company | .633% senior notes due April 2031
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	189	211
Parent Company | .843% senior notes due December 2031
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	58	65
Parent Company | .750% senior notes due March 2032
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	130	145
Parent Company | 1.320% senior notes due December 2032
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	133	148
Parent Company | .844% senior notes due April 2033
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	76	84
Parent Company | 1.488% senior notes due October 2033
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	95	106
Parent Company | 1.682% senior notes due March 2034
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	48	0
Parent Company | 1.600% senior notes due March 2034
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	115	0
Parent Company | .934% senior notes due December 2034
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	62	69
Parent Company | .830% senior notes due March 2035
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	66	74
Parent Company | 1.740% senior notes due March 2036
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	94	0
Parent Company | 1.039% senior notes due April 2036
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	63	70
Parent Company | 1.594% senior notes due September 2037
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	41	45
Parent Company | 1.750% senior notes due October 2038
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	56	62
Parent Company | 1.920% senior notes due March 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	103	0
Parent Company | 1.122% senior notes due December 2039
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	39	44
Parent Company | 1.264% senior notes due April 2041
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	63	70
Parent Company | 2.160% senior notes due March 2044
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	35	0
Parent Company | 2.108% subordinated notes due October 2047
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	375	419
Parent Company | 1.560% senior notes due April 2051
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	125	140
Parent Company | 2.144% senior notes due September 2052
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	75	84
Parent Company | 2.400% senior notes due March 2054
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	122	0
Parent Company | Yen-denominated loan variable interest rate due August 2027
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	74	82
Parent Company | Yen-denominated loan variable interest rate due August 2029
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	160	178
Parent Company | Yen-denominated loan variable interest rate due August 2032
Condensed Financial Statements, Captions [Line Items]
Notes payable and lease obligations	$ 441	$ 492