Segment Information (Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)
Segment Reporting [Abstract]
Number of segments \| Segment	5
Segment Reporting Information [Line Items]
Total assets	$ 719,892	$ 898,764
Percent of total assets from Japan operations	10.00%	10.00%
Assets of disposed subsidiary	$ 0	$ 216,983
Japan
Segment Reporting Information [Line Items]
Total assets	$ 111,000	$ 98,000
Assets, Total \| Geographic Concentration Risk \| Japan
Segment Reporting Information [Line Items]
Percent of total assets from Japan operations	15.00%	11.00%
Brighthouse Financial, Inc [Member]
Segment Reporting Information [Line Items]
Assets of disposed subsidiary		$ 216,983

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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