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, 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
Revenues:
Net investment income	$ 876	$ 869	$ 845	$ 882	$ 858	$ 843	$ 784	$ 794	$ 3,473		$ 3,280		$ 3,007
Realized investment gains (losses)									(349)		(1,552)		(422)
Total revenues	6,375	6,847	5,902	6,240	5,979	5,987	5,088	5,117	25,364		22,171		20,732
Operating expenses:
Interest expense									261		196		149
Other operating expenses									195		182		162
Earnings before income taxes	880	1,480	741	1,202	822	1,092	444	591	4,302		2,950		3,561
Income Tax Expense:
Current									816		891		862
Deferred									620		122		371
Income tax expense	299	463	258	417	284	356	170	202	1,436		1,013		1,233
Net earnings									2,866		1,937		2,328
Parent Company
Revenues:
Dividends from subsidiaries									0	[1]	282	[1]	370	[1]
Management and service fees from subsidiaries									249	[1]	230	[1]	206	[1]
Net investment income									20		10		11
Interest from subsidiaries									7	[1]	8	[1]	8	[1]
Realized investment gains (losses)									1		(1)		0
Change in fair value of the interest rate component of the cross-currency swaps									154		0		0
Other income (loss)									(7)		1		1
Total revenues									424		530		596
Operating expenses:
Interest expense									184		168		140
Other operating expenses									72		69		66
Total operating expenses									256		237		206
Earnings before income taxes									168		293		390
Income Tax Expense:
Current									1		0		0
Deferred									50		(2)		(3)
Income tax expense									51		(2)		(3)
Earnings before equity in undistributed earnings of subsidiaries									117		295		393
Equity in undistributed earnings of subsidiaries									2,749	[1]	1,642	[1]	1,935	[1]
Net earnings									$ 2,866		$ 1,937		$ 2,328

[1] Eliminated in consolidation