Investments - Components of the net unrealized gain on securities that is included in AOCI in the Balance Sheet (Details) - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Unrealized gain on:
Pretax		$ 1,087	$ 622
Deferred Tax		(381)	(218)
Net		706	404
Total investments
Unrealized gain on:
Pretax		1,673	960
Deferred Tax		(586)	(336)
Net		1,087	624
Total fixed maturities
Unrealized gain on:
Pretax		1,406	809
Deferred Tax		(492)	(283)
Net		914	526
Fixed maturities — annuity segment
Unrealized gain on:
Pretax	[1]	1,131	640
Deferred Tax	[1]	(396)	(224)
Net	[1]	735	416
Fixed maturities — all other
Unrealized gain on:
Pretax		275	169
Deferred Tax		(96)	(59)
Net		179	110
Equity securities
Unrealized gain on:
Pretax		267	151
Deferred Tax		(94)	(53)
Net		173	98
Deferred policy acquisition costs — annuity segment
Unrealized gain on:
Pretax		(465)	(273)
Deferred Tax		163	96
Net		(302)	(177)
Annuity benefits accumulated
Unrealized gain on:
Pretax		(141)	(78)
Deferred Tax		49	27
Net		(92)	(51)
Unearned revenue
Unrealized gain on:
Pretax		20	13
Deferred Tax		(7)	(5)
Net		$ 13	$ 8

[1] Net unrealized gains on fixed maturity investments supporting AFG’s annuity benefits accumulated.