Income Taxes - Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets [Abstract]
Employee and retiree benefit plans	$ 481	$ 535
Other insurance and contractholder liabilities	460	465
Net operating losses	128	101
Other accrued liabilities	166	177
Other	140	99
Deferred tax assets before valuation allowance	1,375	1,377
Valuation allowance for deferred tax assets	(87)	(71)
Deferred tax assets, net of valuation allowance	1,288	1,306
Deferred tax liabilities [Abstract]
Depreciation and amortization	781	765
Unrealized appreciation (depreciation) on investments and foreign currency translation	149	152
Other	54	10
Total deferred tax liabilities	984	927
Net deferred income tax assets	304	$ 379
Foreign [Member]
Deferred tax liabilities [Abstract]
Total deferred tax liabilities	$ 140