INVESTMENTS - Commercial Mortgage and Other Loans by Portfolio Segment (Details) - USD ($) $ in Millions	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 10,559		$ 11,224
Percent of total commercial mortgage and other loans	100.00%		100.00%
Allowance for credit losses	$ (422)		$ (355)
Total net commercial mortgage and other loans	10,137		10,869
Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 4,317		$ 4,902
Percent of total commercial mortgage and other loans	41.00%		43.70%
Allowance for credit losses	$ (271)	$ (243)	$ (199)	$ (151)	$ (123)	$ (112)
Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 1,442		$ 1,537
Percent of total commercial mortgage and other loans	13.60%		13.70%
Allowance for credit losses	$ (10)	(12)	$ (14)	(30)	(17)	(16)
Middle market loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 4,387		$ 4,423
Percent of total commercial mortgage and other loans	41.50%		39.40%
Allowance for credit losses	$ (139)	$ (127)	$ (140)	$ (103)	$ (98)	$ (146)
Other loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 413		$ 362
Percent of total commercial mortgage and other loans	3.90%		3.20%
Office \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 1,226		$ 1,361
Percent of total commercial mortgage and other loans	11.60%		12.10%
Office \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 266		$ 300
Percent of total commercial mortgage and other loans	2.50%		2.70%
Retail \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 314		$ 349
Percent of total commercial mortgage and other loans	3.00%		3.10%
Retail \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 208		$ 214
Percent of total commercial mortgage and other loans	2.00%		1.90%
Apartment/Multi-Family \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 1,861		$ 2,201
Percent of total commercial mortgage and other loans	17.60%		19.60%
Apartment/Multi-Family \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 544		$ 572
Percent of total commercial mortgage and other loans	5.10%		5.10%
Industrial \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 101		$ 117
Percent of total commercial mortgage and other loans	1.00%		1.10%
Industrial \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 410		$ 436
Percent of total commercial mortgage and other loans	3.90%		3.90%
Hospitality \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 523		$ 556
Percent of total commercial mortgage and other loans	5.00%		5.00%
Other \| Transitional real estate loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 292		$ 318
Percent of total commercial mortgage and other loans	2.80%		2.80%
Other \| Commercial mortgage loans
Participating Mortgage Loans [Line Items]
Commercial mortgage and other loans, gross	$ 14		$ 15
Percent of total commercial mortgage and other loans	0.10%		0.10%

AFLAC INC 10-Q