Federal Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Reconciliation of effective tax rate differences [Abstract]
Tax rate times pre-tax income	$ 146	$ 54	$ 409	$ 347
Tax-preferred investment income	(32)	(47)	(101)	(107)
Tax credits	(17)	(14)	(38)	(35)
Change in uncertain tax positions	(83)	0	(83)	0
Other items	31	1	37	9
Federal income tax expense (benefit)	45	(6)	224	214
Effective tax rate	11.00%	(4.00%)	19.00%	22.00%
Reconciliation of unrecognized tax benefits [Roll Forward]
Balance as of beginning-of-year			316	318
Decreases for prior year tax positions			(200)	(12)
Increases for current year tax positions			27	2
Decreases for lapse of statute of limitations			(74)	0
Balance as of end-of-period	69	308	69	308
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 94	$ 231	$ 94	$ 231