Segment Information (Reconciliation of Assets From Segments to Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	$ 336,016	$ 299,145
Annuities Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	166,639	145,462
Retirement Plan Services Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	40,190	35,742
Life Insurance Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	93,327	82,153
Group Protection Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	9,468	8,495
Other Operations [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total assets	$ 26,392	$ 27,293