Schedule III - Supplementary Insurance Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	$ 10,654				$ 9,734				$ 10,654	$ 9,734
Future Policy Benefits & Unpaid Policy Claims	83,259				75,822				83,259	75,822
Unearned Premiums	1,704				1,197				1,704	1,197
Other policyholders' funds	9,630				5,437				9,630	5,437
Premium Revenue	5,324	5,210	4,956	4,872	4,785	4,607	4,333	4,348	20,362	18,073	16,621
Net Investment Income	858	843	784	794	789	765	727	726	3,280	3,007	2,765
Benefits and claims									13,749	12,106	11,308
Amortization of Deferred Policy Acquisition Costs									1,102	1,030	942
Other Operating Expenses									4,328	4,011	3,769
Premiums Written									23,767	19,154	16,928
Aflac Japan
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	7,733				6,964				7,733	6,964
Future Policy Benefits & Unpaid Policy Claims	75,578				68,615				75,578	68,615
Unearned Premiums	1,602				1,092				1,602	1,092
Other policyholders' funds	9,342				5,165				9,342	5,165
Premium Revenue									15,619	13,487	12,178
Net Investment Income									2,688	2,453	2,265
Benefits and claims									11,037	9,553	8,746
Amortization of Deferred Policy Acquisition Costs									686	597	523
Other Operating Expenses									2,772	2,544	2,417
Premiums Written									19,034	14,586	12,485
Aflac U.S.
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	2,921				2,770				2,921	2,770
Future Policy Benefits & Unpaid Policy Claims	7,679				7,204				7,679	7,204
Unearned Premiums	102				105				102	105
Other policyholders' funds	288				272				288	272
Premium Revenue									4,743	4,586	4,444
Net Investment Income									588	549	499
Benefits and claims									2,713	2,553	2,561
Amortization of Deferred Policy Acquisition Costs									416	433	419
Other Operating Expenses									1,295	1,236	1,197
Premiums Written									4,733	4,568	4,443
All Other
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	0				0				0	0
Future Policy Benefits & Unpaid Policy Claims	2				3				2	3
Unearned Premiums	0				0				0	0
Other policyholders' funds	0				0				0	0
Premium Revenue									0	0	(1)
Net Investment Income									4	5	1
Benefits and claims									(1)	0	1
Amortization of Deferred Policy Acquisition Costs									0	0	0
Other Operating Expenses									261	231	155
Premiums Written									$ 0	$ 0	$ 0