Schedule II - Aflac Incorporated (Parent Only) - Condensed Statements of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Cash flows from operating activities:
Net earnings	$ 2,866		$ 1,937		$ 2,328
Adjustments to reconcile net earnings to net cash provided from operating activities:
Change in income tax liabilities	712		266		137
Other, net	(34)		(33)		(97)
Net cash provided (used) by operating activities	14,952		10,842		6,989
Cash flows from investing activities:
Fixed maturity securities sold	7,385		14,385		2,724
Fixed maturity securities purchased	(19,533)		(8,392)		(9,943)
Other, net	514		(62)		(28)
Net cash provided (used) by investing activities	(16,952)		(10,829)		(7,432)
Cash flows from financing activities:
Purchases of treasury stock	(118)		(308)		(121)
Proceeds from borrowings	1,506		620		748
Principal payments under debt obligations	(341)		(462)		(451)
Dividends paid to shareholders	(603)		(552)		(535)
Treasury stock reissued	32		26		45
Net change in amount due to/from subsidiaries	12		7		56
Net cash provided (used) by financing activities	1,945		64		161
Net change in cash and cash equivalents	(208)		128		(202)
Cash and cash equivalents, beginning of period	2,249		2,121		2,323
Cash and cash equivalents, end of period	2,041		2,249		2,121
Parent Company
Cash flows from operating activities:
Net earnings	2,866		1,937		2,328
Adjustments to reconcile net earnings to net cash provided from operating activities:
Equity in undistributed earnings of subsidiaries	(2,749)	[1]	(1,642)	[1]	(1,935)	[1]
Change in income tax liabilities	111		(52)		(77)
Other, net	(242)		145		153
Net cash provided (used) by operating activities	(14)		388		469
Cash flows from investing activities:
Fixed maturity securities sold	13		4		12
Fixed maturity securities purchased	(26)		(10)		(8)
Other investments sold (purchased)	(3)		0		0
Purchase of subsidiary	0		0		0
Additional capitalization of subsidiaries	0	[1]	(40)	[1]	0	[1]
Other, net	0		0		0
Net cash provided (used) by investing activities	(16)		(46)		4
Cash flows from financing activities:
Purchases of treasury stock	(118)		(308)		(121)
Proceeds from borrowings	1,506		620		748
Principal payments under debt obligations	(380)		(459)		(447)
Dividends paid to shareholders	(603)		(552)		(535)
Treasury stock reissued	70		26		45
Proceeds from exercise of stock options	21		14		27
Net change in amount due to/from subsidiaries	(21)	[1]	9	[1]	5	[1]
Net cash provided (used) by financing activities	475		(650)		(278)
Net change in cash and cash equivalents	445		(308)		195
Cash and cash equivalents, beginning of period	385		693		498
Cash and cash equivalents, end of period	$ 830		$ 385		$ 693

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