Income Taxes - Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets [Abstract]
Employee and retiree benefit plans	$ 535	$ 597
Other insurance and contractholder liabilities	465	440
Net operating losses	101	72
Other accrued liabilities	177	203
Other	99	105
Deferred tax assets before valuation allowance	1,377	1,417
Valuation allowance for deferred tax assets	(71)	(49)
Deferred tax assets, net of valuation allowance	1,306	1,368
Deferred tax liabilities [Abstract]
Depreciation and amortization	765	755
Unrealized appreciation (depreciation) on investments and foreign currency translation	152	298
Other	10	22
Total deferred tax liabilities	927	1,075
Net deferred income tax assets	379	$ 293
Deferred tax liabilities attributable to foreign jurisdictions	$ 150