These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the treasury rate plus 20 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.

1.125% senior notes due March 2026

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount | $

$ 400

Debt instrument, interest rate

1.125%

Debt instrument, redemption, description

These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the yield to maturity for a U.S. Treasury security with a maturity comparable to the remaining term of the notes, plus 10 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.

Parent Company

Condensed Financial Statements, Captions [Line Items]

Number of series of senior notes issued through a U.S. public debt offering (in series) | series

Parent Company | Senior notes

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount

¥ 82.0

Parent Company | .633% senior notes due April 2031

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount

¥ 30.0

Debt instrument, interest rate

0.633%

Parent Company | .844% senior notes due April 2033

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount

¥ 12.0

Debt instrument, interest rate

0.844%

Parent Company | 1.039% senior notes due April 2036

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount

¥ 10.0

Debt instrument, interest rate

1.039%

Parent Company | 1.264% senior notes due April 2041

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount

¥ 10.0

Debt instrument, interest rate

1.264%

Parent Company | 1.560% senior notes due April 2051

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount

¥ 20.0

Debt instrument, interest rate

1.56%

Parent Company | 3.625% senior notes paid May 2021

Condensed Financial Statements, Captions [Line Items]

Debt instrument, interest rate

3.625%

Repayments of debt | $

$ 700

Parent Company | 1.125% senior notes due March 2026

Condensed Financial Statements, Captions [Line Items]

Debt instrument, principal amount | $

$ 400

Debt instrument, interest rate

1.125%

Debt instrument, redemption, description

These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the yield to maturity for a U.S. Treasury security with a maturity comparable to the remaining term of the notes, plus 10 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.

Schedule II - Aflac Incorporated (Parent Only) - Additional Information (Detail) $ in Millions, ¥ in Billions	1 Months Ended
	May 31, 2021 USD ($)	Mar. 31, 2021 JPY (¥) series	Jun. 30, 2013 USD ($)	Dec. 31, 2021 JPY (¥)	Apr. 30, 2021 JPY (¥) series	Mar. 31, 2021 USD ($) series	Dec. 31, 2020 JPY (¥) series	Oct. 31, 2018 JPY (¥) series	Sep. 30, 2017 USD ($) series
Condensed Financial Statements, Captions [Line Items]
Number of series of senior notes issued through a U.S. public debt offering (in series) \| series		4			5	4	4	3	2
Senior notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount		¥ 57.0			¥ 82.0		¥ 38.0	¥ 53.4	$ 700
.633% senior notes due April 2031
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 30.0	¥ 30.0		¥ 30.0
Debt instrument, interest rate				0.633%	0.633%		0.633%
.844% senior notes due April 2033
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 12.0	¥ 12.0		¥ 12.0
Debt instrument, interest rate				0.844%	0.844%		0.844%
1.039% senior notes due April 2036
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 10.0	¥ 10.0		¥ 10.0
Debt instrument, interest rate				1.039%	1.039%		1.039%
1.264% senior notes due April 2041
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 10.0	¥ 10.0		¥ 10.0
Debt instrument, interest rate				1.264%	1.264%		1.264%
1.560% senior notes due April 2051
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 20.0	¥ 20.0
Debt instrument, interest rate				1.56%	1.56%		1.56%
3.625% senior notes paid May 2021
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount \| $			$ 700
Debt instrument, interest rate	3.625%		3.625%	3.625%			3.625%
Repayments of debt \| $	$ 700
Debt instrument, redemption, description			These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the treasury rate plus 20 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.
1.125% senior notes due March 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount \| $						$ 400
Debt instrument, interest rate		1.125%		1.125%		1.125%	1.125%
Debt instrument, redemption, description		These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the yield to maturity for a U.S. Treasury security with a maturity comparable to the remaining term of the notes, plus 10 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.
Parent Company
Condensed Financial Statements, Captions [Line Items]
Number of series of senior notes issued through a U.S. public debt offering (in series) \| series					5
Parent Company \| Senior notes
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount					¥ 82.0
Parent Company \| .633% senior notes due April 2031
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 30.0	¥ 30.0		¥ 30.0
Debt instrument, interest rate				0.633%	0.633%		0.633%
Parent Company \| .844% senior notes due April 2033
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 12.0	¥ 12.0		¥ 12.0
Debt instrument, interest rate				0.844%	0.844%		0.844%
Parent Company \| 1.039% senior notes due April 2036
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 10.0	¥ 10.0		¥ 10.0
Debt instrument, interest rate				1.039%	1.039%		1.039%
Parent Company \| 1.264% senior notes due April 2041
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 10.0	¥ 10.0		¥ 10.0
Debt instrument, interest rate				1.264%	1.264%		1.264%
Parent Company \| 1.560% senior notes due April 2051
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount				¥ 20.0	¥ 20.0		¥ 20.0
Debt instrument, interest rate				1.56%	1.56%		1.56%
Parent Company \| 3.625% senior notes paid May 2021
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate	3.625%			3.625%			3.625%
Repayments of debt \| $	$ 700
Parent Company \| 1.125% senior notes due March 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, principal amount \| $						$ 400
Debt instrument, interest rate		1.125%		1.125%		1.125%	1.125%
Debt instrument, redemption, description		These notes are redeemable at the Parent Company's option in whole at any time or in part from time to time at a redemption price equal to the greater of: (i) the aggregate principal amount of the notes to be redeemed or (ii) the amount equal to the sum of the present values of the remaining scheduled payments for principal of and interest on the notes to be redeemed, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis at the yield to maturity for a U.S. Treasury security with a maturity comparable to the remaining term of the notes, plus 10 basis points, plus in each case, accrued and unpaid interest on the principal amount of the notes to be redeemed to, but excluding, such redemption date.