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, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Revenues:
Net investment income	$ 826	$ 821	$ 813	$ 833	$ 876	$ 869	$ 845	$ 882	$ 3,293		$ 3,473		$ 3,280
Realized investment gains (losses)									399		(349)		(1,552)
Total revenues	5,801	5,886	6,044	6,208	6,375	6,847	5,902	6,240	23,939		25,364		22,171
Operating expenses:
Interest expense									293		261		196
Other operating expenses									193		195		182
Earnings before income taxes	1,028	1,069	1,358	1,361	880	1,480	741	1,202	4,816		4,302		2,950
Income Tax Expense:
Current									1,236		816		891
Deferred									422		620		122
Total income tax expense	353	367	469	469	299	463	258	417	1,658		1,436		1,013
Net earnings									3,158		2,866		1,937
Parent Company
Revenues:
Dividends from subsidiaries									962	[1]	0	[1]	282	[1]
Management and service fees from subsidiaries									292	[1]	249	[1]	230	[1]
Net investment income									11		20		10
Interest from subsidiaries									7	[1]	7	[1]	8	[1]
Realized investment gains (losses)									10		1		(1)
Change in fair value of the interest rate component of the cross-currency swaps									274		154		0
Other income (loss)									1		(7)		1
Total revenues									1,557		424		530
Operating expenses:
Interest expense									208		184		168
Other operating expenses									79		72		69
Total operating expenses									287		256		237
Earnings before income taxes									1,270		168		293
Income Tax Expense:
Current									0		1		0
Deferred									98		50		(2)
Total income tax expense									98		51		(2)
Earnings before equity in undistributed earnings of subsidiaries									1,172		117		295
Equity in undistributed earnings of subsidiaries									1,986	[1]	2,749	[1]	1,642	[1]
Net earnings									$ 3,158		$ 2,866		$ 1,937

[1] Eliminated in consolidation