SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION - (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	$ 8,993				$ 8,511				$ 8,993	$ 8,511
Future Policy Benefits & Unpaid Policy Claims	80,151				73,489				80,151	73,489
Unearned premiums	6,916				7,857				6,916	7,857
Other policyholders' funds	6,659				6,285				6,659	6,285
Premiums Earned, Net	4,778	$ 5,022	$ 4,823	$ 4,602	4,394	$ 4,380	$ 4,364	$ 4,432	19,225	17,570	$ 19,072
Net investment income	813	$ 842	$ 822	$ 801	792	$ 784	$ 777	$ 782	3,278	3,135	3,319
Benefits and claims, net									12,919	11,746	12,937
Amortization of deferred policy acquisition costs									1,141	1,066	1,108
Other operating Expenses									4,432	4,198	4,192
Premiums written									18,214	17,083	18,550
Aflac Japan
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	5,765				5,370				5,765	5,370	5,211
Future Policy Benefits & Unpaid Policy Claims	70,684				64,437				70,684	64,437
Unearned premiums	6,798				7,739				6,798	7,739
Other policyholders' funds	6,659				6,285				6,659	6,285
Premiums Earned, Net									13,537	12,046	13,861
Net investment income									2,554	2,436	2,662
Benefits and claims, net									9,828	8,705	10,084
Amortization of deferred policy acquisition costs									644	578	649
Other operating Expenses									2,326	2,055	2,364
Premiums written									12,762	11,740	13,352
Aflac U.S.
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	3,228				3,141				3,228	3,141	3,062
Future Policy Benefits & Unpaid Policy Claims	10,094				9,696				10,094	9,696
Unearned premiums	118				118				118	118
Other policyholders' funds	0				0				0	0
Premiums Earned, Net									5,454	5,347	5,211
Net investment income									703	678	645
Benefits and claims, net									2,869	2,873	2,853
Amortization of deferred policy acquisition costs									497	488	459
Other operating Expenses									1,593	1,570	1,474
Premiums written									5,452	5,343	5,198
All other
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	0				0				0	0
Future Policy Benefits & Unpaid Policy Claims	91				43				91	43
Unearned premiums	0				0				0	0
Other policyholders' funds	0				0				0	0
Premiums Earned, Net									234	177	0
Net investment income									21	21	12
Benefits and claims, net									222	168	0
Amortization of deferred policy acquisition costs									0	0	0
Other operating Expenses									513	573	354
Premiums written									0	0	$ 0
Intercompany eliminations
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	0				0				0	0
Future Policy Benefits & Unpaid Policy Claims	(718)				(687)				(718)	(687)
Unearned premiums	0				0				0	0
Other policyholders' funds	$ 0				$ 0				$ 0	$ 0