Segment Information (Schedule Of Disaggregation Of Revenue) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 312
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	21
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	291
Fee Income [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	180
Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	132
Annuities Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	253
Annuities Segment [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	18
Annuities Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	235
Annuities Segment [Member] | Fee Income [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	133
Annuities Segment [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	120
Retirement Plan Services Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	46
Retirement Plan Services Segment [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1
Retirement Plan Services Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	45
Retirement Plan Services Segment [Member] | Fee Income [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	42
Retirement Plan Services Segment [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4
Life Insurance Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8
Life Insurance Segment [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2
Life Insurance Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6
Life Insurance Segment [Member] | Fee Income [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5
Life Insurance Segment [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3
Group Protection Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5
Group Protection Segment [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5
Group Protection Segment [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 5