Schedule II - Aflac Incorporated (Parent Only) - Condensed Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Investments and cash:
Other investments	$ 174		$ 168
Cash and cash equivalents	2,041		2,249		2,121	2,323
Total investments and cash	118,219		103,462
Other assets	835	[1]	887	[1]
Total assets	131,094		116,237		100,243
Liabilities:
Notes payable	4,343		3,275
Income taxes	3,858		2,308
Other liabilities	2,680	[2]	2,267	[2]
Total liabilities	115,116		103,291
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2012 and 2011; issued 665,239 shares in 2012 and 663,639 shares in 2011	67		66
Additional paid-in capital	1,505		1,408
Retained earnings	17,387		15,148
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains	333		984
Unrealized gains (losses) on investment securities	2,570		1,143
Unrealized gains (losses) on derivatives	(5)		9
Pension liability adjustment	(183)		(171)
Treasury stock, at average cost	(5,696)		(5,641)
Total shareholders' equity	15,978		12,946		10,540
Total liabilities and shareholders' equity	131,094		116,237
Parent Company
Investments and cash:
Fixed maturity securities available for sale, at fair value (amortized cost $0 in 2012 and $120 in 2011)	156		138
Investments in subsidiaries	19,001	[3]	15,531	[3]
Other investments	14		15
Cash and cash equivalents	830		385		693	498
Total investments and cash	20,001		16,069
Due from subsidiaries	156	[3]	134	[3]
Other assets	257		79
Total assets	20,414		16,282
Liabilities:
Notes payable	4,367		3,345
Employee benefit plans	255		175
Income taxes	(232)		(311)
Other liabilities	46		127
Total liabilities	4,436		3,336
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2012 and 2011; issued 665,239 shares in 2012 and 663,639 shares in 2011	67		66
Additional paid-in capital	1,505		1,408
Retained earnings	17,387		15,148
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains	333		984
Unrealized gains (losses) on investment securities	2,570		1,143
Unrealized gains (losses) on derivatives	(5)		9
Pension liability adjustment	(183)		(171)
Treasury stock, at average cost	(5,696)		(5,641)
Total shareholders' equity	15,978		12,946
Total liabilities and shareholders' equity	$ 20,414		$ 16,282

[1] Includes $191 in 2012 and $375 in 2011 of derivatives from consolidated variable interest entities

[2] Includes $399 in 2012 and $531 in 2011 of derivatives from consolidated variable interest entities

[3]