Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred income tax assets:
Liabilities for future policy benefits and claims	$ 1,320	$ 1,615
Investment impairments and write-downs	105	118
Investment related	104
Deferred compensation	310	274
Loss carryovers and tax credit carryforwards	43	134
Other	50	92
Gross deferred income tax assets	1,932	2,233
Less: Valuation allowance	(16)	(5)
Total deferred income tax assets	1,916	2,228
Deferred income tax liabilities:
Deferred acquisition costs	701	674
Investment related		260
Deferred sales inducement costs	142	180
Net unrealized gains on available-for-sale securities	708	457
Depreciation expense	164	182
Intangible assets	74	60
Other	82	71
Gross deferred income tax liabilities	1,871	1,884
Net deferred income tax liabilities	45	344
State net operating losses	39
Reconciliation of gross unrecognized tax benefits (expense)
Gross unrecognized tax benefits, balance at the beginning of the period	184	75	(33)
Additions based on tax positions related to the current year	2	1	2
Additions for tax positions of prior years	25	95	57
Reductions for tax positions of prior years	(83)	(8)	(42)
Settlements	(12)	21	91
Gross unrecognized tax benefits, balance at the end of the period	116	184	75
Unrecognized tax benefits (net of federal tax benefits) that would impact the effective tax rate	38	38	54
Estimated decrease in amount of unrecognized tax benefits in next 12 months	76
Increase (reduction) in interest and penalties	1	66	(17)
Accrued interest and penalties	(36)	(37)
Income tax provision (benefit) amounts of items comprising other comprehensive income (loss)
Net unrealized securities gains	238	90	191
Net unrealized derivatives gains (losses)	4	(15)	8
Defined benefit plans	(9)	(28)	(2)
Foreign currency translation	7	(1)	(6)
Net income tax provision (benefit)	$ 240	$ 46	$ 191