Income Taxes (Deferred Income Tax Assets and Liabilities) (Details 3) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets:
Liabilities for policyholder account balances, future policy benefits and claims	$ 620	$ 1,177
Deferred compensation	345	439
Investment related	245	253
Postretirement benefits	34	62
Deferred Tax Assets, Unrealized Currency Losses	0	73
Other	66	68
Gross deferred income tax assets	1,310	2,072
Less: Valuation allowance	17	11
Total deferred income tax assets	1,293	2,061
Deferred income tax liabilities:
Deferred acquisition costs	446	717
Net unrealized gains on Available-for-Sale securities	162	264
Depreciation expense	93	146
Deferred sales inducement costs	62	113
Intangible assets	93	126
Goodwill	52	74
Other	7	2
Gross deferred income tax liabilities	915	1,442
Net deferred income tax liabilities	378	619
State net operating losses	17
Valuation allowance	$ 17	$ 11