SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION - (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	$ 8,273				$ 8,798				$ 8,273	$ 8,798
Future Policy Benefits & Unpaid Policy Claims	69,276				72,899				69,276	72,899
Unearned premiums	8,626				10,642				8,626	10,642
Other policyholders' funds	6,031				5,861				6,031	5,861
Net earned premiums	4,489	4,841	4,888	4,854	4,910	5,028	5,013	5,184	19,072	20,135	22,148
Net investment income	808	841	843	827	826	821	813	833	3,319	3,293	3,473
Benefits and claims, net									12,937	13,813	15,330
Amortization of deferred policy acquisition costs									1,108	1,074	1,117
Other Operating Expenses									4,192	4,236	4,615
Premiums Written									18,550	21,104	28,650
Aflac Japan
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	5,211				5,819				5,211	5,819	6,801
Future Policy Benefits & Unpaid Policy Claims	60,036				64,122				60,036	64,122
Unearned premiums	8,509				10,520				8,509	10,520
Other policyholders' funds	6,030				5,660				6,030	5,660
Net earned premiums									13,861	14,982	17,151
Net investment income									2,662	2,651	2,845
Benefits and claims, net									10,084	10,924	12,496
Amortization of deferred policy acquisition costs									649	641	716
Other Operating Expenses									2,364	2,495	2,937
Premiums Written									13,352	15,960	23,662
Aflac U.S.
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	3,062				2,979				3,062	2,979	2,857
Future Policy Benefits & Unpaid Policy Claims	9,239				8,775				9,239	8,775
Unearned premiums	117				122				117	122
Other policyholders' funds	0				201				0	201
Net earned premiums									5,211	5,153	4,996
Net investment income									645	632	613
Benefits and claims, net									2,853	2,889	2,834
Amortization of deferred policy acquisition costs									459	433	400
Other Operating Expenses									1,474	1,431	1,397
Premiums Written									5,198	5,144	4,988
All other
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	0				0				0	0
Future Policy Benefits & Unpaid Policy Claims	1				2				1	2
Unearned premiums	0				0				0	0
Other policyholders' funds	1				0				1	0
Net earned premiums									0	0	1
Net investment income									12	10	15
Benefits and claims, net									0	0	0
Amortization of deferred policy acquisition costs									0	0	1
Other Operating Expenses									354	310	281
Premiums Written									$ 0	$ 0	$ 0