Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Deferred income tax assets:
Liabilities for future policy benefits and claims	$ 1,615	$ 1,329
Investment impairments and write-downs	118	119
Deferred compensation	274	241
Investment related		56
Loss carryovers and tax credit carryforwards	134	134
Other	89	70
Gross deferred income tax assets	2,230	1,949
Less: Valuation allowance	(5)
Total deferred income tax assets	2,225	1,949
Deferred income tax liabilities:
Deferred tax liabilities, deferred expense, deferred policy acquisition cost	1,418	1,473
Investment related	260
Deferred sales inducement costs	180	191
Net unrealized gains on available-for-sale securities	396	312
Depreciation expense	182	138
Intangible assets	60	52
Other	71	85
Gross deferred income tax liabilities	2,567	2,251
Net deferred income tax	(342)	(302)
Maximum period for recognizing capital losses (in years)	5
Capital loss carryforwards	30
Tax credit carryforwards	65
State net operating losses	39
Reconciliation of gross unrecognized tax benefits (expense)
Gross unrecognized tax benefits, balance at the beginning of the period	75	(33)	(56)
Additions based on tax positions related to the current year	1	2	1
Additions for tax positions of prior years	95	57	45
Reductions for tax positions of prior years	(8)	(42)	(23)
Settlements	21	91
Gross unrecognized tax benefits, balance at the end of the period	184	75	(33)
Unrecognized tax benefits (net of federal tax benefits) that would impact the effective tax rate	38	54	81
Increase (reduction) in interest and penalties	66	(5)	1
Accrued interest and penalties	(37)	29
Estimated decrease in amount of unrecognized tax benefits in next 12 months, low end of the range	150
Estimated decrease in amount of unrecognized tax benefits in next 12 months, high end of the range	160
Income tax provision (benefit) amounts of items comprising other comprehensive income (loss)
Net unrealized securities gains	77	167	753
Net unrealized derivatives gains	(15)	8	6
Defined benefit plans	(28)	(2)	10
Foreign currency translation adjustment	(1)	(6)	15
Net income tax provision (benefit)	$ 33	$ 167	$ 784