Segment Information (Total Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 207,226	$ 212,045
Annuities
Segment Reporting Information [Line Items]
Total assets	148,753	149,920
Life
Segment Reporting Information [Line Items]
Total assets	15,056	13,044
Run-off
Segment Reporting Information [Line Items]
Total assets	34,020	36,719
Corporate & Other
Segment Reporting Information [Line Items]
Total assets	$ 9,397	$ 12,362