Segment Information (Reconciliation of Assets From Segments to Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	$ 299,145	$ 281,872
Annuities Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	145,462	144,035
Retirement Plan Services Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	35,742	37,077
Life Insurance Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	82,153	81,565
Group Protection Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	8,495	4,033
Other Operations [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	$ 27,293	$ 15,162