Segment Information (Total Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 204,579	$ 212,045
Annuities
Segment Reporting Information [Line Items]
Total assets	146,905	149,920
Life
Segment Reporting Information [Line Items]
Total assets	14,192	13,044
Run-off
Segment Reporting Information [Line Items]
Total assets	32,458	36,719
Corporate & Other
Segment Reporting Information [Line Items]
Total assets	$ 11,024	$ 12,362