Schedule II - Aflac Incorporated (Parent Only) - Condensed Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2008
Investments and cash:
Other investments	$ 168		$ 135
Cash and cash equivalents	2,249		2,121		2,323	941
Total investments and cash	103,462		88,230
Other assets	887	[1]	1,056	[1]
Total assets	117,102		101,039
Liabilities:
Income taxes	2,613		1,969
Other liabilities	2,267	[2]	2,329	[2]
Total liabilities	103,596		89,983
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2011 and 2010; issued 663,639 shares in 2011 and 662,660 shares in 2010	66		66
Additional paid-in capital	1,408		1,320
Retained earnings	15,583		14,194
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains	1,109		926
Unrealized gains (losses) on investment securities	1,143		33
Unrealized gains (losses) on derivatives	9		31
Pension liability adjustment	(171)		(128)
Treasury stock, at average cost	(5,641)		(5,386)
Total shareholders' equity	13,506		11,056		8,417
Total liabilities and shareholders' equity	117,102		101,039
Parent Company
Investments and cash:
Fixed maturity securities available for sale, at fair value (amortized cost $120 in 2011 and $114 in 2010)	138		120
Investments in subsidiaries	16,091	[3]	13,125	[3]
Other investments	15		6
Cash and cash equivalents	385		693		498	258
Total investments and cash	16,629		13,944
Due from subsidiaries	134	[3]	140	[3]
Other assets	79		80
Total assets	16,842		14,164
Liabilities:
Notes payable	3,345		3,098
Employee benefit plans	175		154
Income taxes	(311)		(287)
Other liabilities	127		143
Total liabilities	3,336		3,108
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2011 and 2010; issued 663,639 shares in 2011 and 662,660 shares in 2010	66		66
Additional paid-in capital	1,408		1,320
Retained earnings	15,583		14,194
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains	1,109		926
Unrealized gains (losses) on investment securities	1,143		33
Unrealized gains (losses) on derivatives	9		31
Pension liability adjustment	(171)		(128)
Treasury stock, at average cost	(5,641)		(5,386)
Total shareholders' equity	13,506		11,056
Total liabilities and shareholders' equity	$ 16,842		$ 14,164

[1] Includes $375 in 2011 and $564 in 2010 of derivatives from consolidated variable interest entities

[2] Includes $531 in 2011 and $741 in 2010 of derivatives from consolidated variable interest entities

[3] Eliminated in consolidation