Schedule II - Aflac Incorporated (Parent Only) - Condensed Statement of Earnings (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
Revenues:
Net Investment Income	$ 858	$ 843	$ 784	$ 794	$ 789	$ 765	$ 727	$ 726	$ 3,280		$ 3,007		$ 2,765
Realized investment gains (losses)									(1,552)		(422)		(1,212)
Total revenues	5,979	5,987	5,088	5,117	5,294	5,394	4,980	5,065	22,171		20,732		18,254
Operating expenses:
Interest expense									196		149		72
Other operating expenses									182		163		152
Earnings before income taxes	834	1,105	453	600	667	1,055	889	974	2,992		3,585		2,235
Income tax expense (benefit):
Current									891		862		830
Deferred									137		379		(92)
Total income taxes	(288)	(361)	(173)	(205)	(230)	(365)	(308)	(338)	1,028		1,241		738
Net earnings									1,964		2,344		1,497
Parent Company
Revenues:
Dividends from subsidiaries									282	[1]	370	[1]	464	[1]
Management and service fees from subsidiaries									230	[1]	206	[1]	124	[1]
Net Investment Income									10		11		9
Interest from subsidiaries									8	[1]	8	[1]	9	[1]
Realized investment gains (losses)									(1)		0		0
Change in fair value of the interest rate component of the cross-currency swaps									0		0		(4)
Other income (loss)									1		1		(11)
Total revenues									530		596		591
Operating expenses:
Interest expense									168		140		73
Other operating expenses									69		66		65
Total operating expenses									237		206		138
Earnings before income taxes									293		390		453
Income tax expense (benefit):
Current									0		0		13
Deferred									(2)		(3)		(4)
Total income taxes									(2)		(3)		9
Earnings before equity in undistributed earnings of subsidiaries									295		393		444
Equity in undistributed earnings of subsidiaries									1,669	[1]	1,951	[1]	1,053	[1]
Net earnings									$ 1,964		$ 2,344		$ 1,497

[1] Eliminated in consolidation