SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION - (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	$ 9,658				$ 9,789				$ 9,658	$ 9,789
Future Policy Benefits & Unpaid Policy Claims	80,497				83,259				80,497	83,259
Unearned premiums	2,158				1,704				2,158	1,704
Other policyholders' funds	15,294				9,630				15,294	9,630
Premium Revenue	5,643	5,660	5,467	5,378	5,324	5,210	4,956	4,872	22,148	20,362	18,073
Net investment income	876	869	845	882	858	843	784	794	3,473	3,280	3,007
Benefits and claims									15,330	13,749	12,106
Amortization of deferred policy acquisition costs									1,117	1,033	958
Other Operating Expenses									4,615	4,439	4,107
Premiums Written									28,650	23,767	19,154
Aflac Japan
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	6,801				7,102				6,801	7,102
Future Policy Benefits & Unpaid Policy Claims	72,286				75,578				72,286	75,578
Unearned premiums	2,057				1,602				2,057	1,602
Other policyholders' funds	14,995				9,342				14,995	9,342
Premium Revenue									17,151	15,619	13,487
Net investment income									2,845	2,688	2,453
Benefits and claims									12,496	11,037	9,553
Amortization of deferred policy acquisition costs									716	650	563
Other Operating Expenses									2,937	2,837	2,601
Premiums Written									23,662	19,034	14,586
Aflac U.S.
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	2,857				2,687				2,857	2,687
Future Policy Benefits & Unpaid Policy Claims	8,209				7,679				8,209	7,679
Unearned premiums	101				102				101	102
Other policyholders' funds	298				288				298	288
Premium Revenue									4,996	4,743	4,586
Net investment income									613	588	549
Benefits and claims									2,834	2,713	2,553
Amortization of deferred policy acquisition costs									400	383	395
Other Operating Expenses									1,397	1,341	1,276
Premiums Written									4,988	4,733	4,568
All Other
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	0				0				0	0
Future Policy Benefits & Unpaid Policy Claims	2				2				2	2
Unearned premiums	0				0				0	0
Other policyholders' funds	1				0				1	0
Premium Revenue									1	0	0
Net investment income									15	4	5
Benefits and claims									0	(1)	0
Amortization of deferred policy acquisition costs									1	0	0
Other Operating Expenses									281	261	230
Premiums Written									$ 0	$ 0	$ 0