Schedule II - Aflac Incorporated (Parent Only) - Condensed Balance Sheet (Detail 1) - USD ($) $ in Millions		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments and cash:
Other investments		$ 1,450	[1]	$ 294
Cash and cash equivalents		4,859		4,350	$ 4,658	$ 2,543
Total investments and cash		116,361		105,897
Other assets	[2]	2,609		1,948
Total assets		129,819		118,256	119,727
Liabilities:
Notes payable		5,339		4,951
Other liabilities	[3]	4,338		2,665
Total liabilities		109,337		100,548
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2016 and 2015; issued 671,249 shares in 2016 and 669,723 shares in 2015		67		67
Additional paid-in capital		1,976		1,828
Retained earnings		25,981		24,007
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains (losses)		(1,983)		(2,196)
Unrealized gains (losses) on investment securities		4,805		2,986
Unrealized gains (losses) on derivatives		(24)		(26)
Pension liability adjustment		(168)		(139)
Treasury stock, at average cost		(10,172)		(8,819)
Total shareholders' equity		20,482		17,708	18,347
Total liabilities and shareholders' equity		129,819		118,256
Parent Company
Investments and cash:
Fixed maturity securities available for sale, at fair value (amortized cost $483 in 2016 and $481 in 2015)		496		493
Investments in subsidiaries	[4]	23,353		20,500
Other investments		3		9
Cash and cash equivalents		2,037		1,721	$ 1,638	$ 1,081
Total investments and cash		25,889		22,723
Due from subsidiaries	[4]	75		113
Income taxes receivable		103		0
Other assets		497		542
Total assets		26,564		23,378
Liabilities:
Income taxes		0		8
Employee benefit plans		293		274
Notes payable		5,339		4,968
Other liabilities		450		420
Total liabilities		6,082		5,670
Shareholders' equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2016 and 2015; issued 671,249 shares in 2016 and 669,723 shares in 2015		67		67
Additional paid-in capital		1,976		1,828
Retained earnings		25,981		24,007
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains (losses)		(1,983)		(2,196)
Unrealized gains (losses) on investment securities		4,805		2,986
Unrealized gains (losses) on derivatives		(24)		(26)
Pension liability adjustment		(168)		(139)
Treasury stock, at average cost		(10,172)		(8,819)
Total shareholders' equity		20,482		17,708
Total liabilities and shareholders' equity		$ 26,564		$ 23,378

[1] Includes $819 in 2016 of loan receivables from consolidated variable interest entities

[2] Includes $127 in 2016 and $102 in 2015 of derivatives from consolidated variable interest entities

[3] Includes $146 in 2016 and $293 in 2015 of derivatives from consolidated variable interest entities

[4] Eliminated in consolidation