Investments (Commercial Mortgage Loans By Year Of Origination) (Details) - Commercial [Member] $ in Millions	Jun. 30, 2020 USD ($) item	Dec. 31, 2019 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 958
2019	3,450
2018	2,606
2017	1,987
2016	1,937
2015 and prior	5,143
Total	16,081	$ 15,606
Loan-to-value ratio, less than 65% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	899
2019	2,933
2018	2,343
2017	1,815
2016	1,714
2015 and prior	4,976
Total	$ 14,680	14,206
2020 | item	3.28
2019 | item	2.30
2018 | item	2.23
2017 | item	2.41
2016 | item	2.42
2015 and prior | item	2.53
Loan-to-value ratio, 65% to 74% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 59
2019	517
2018	263
2017	172
2016	216
2015 and prior	166
Total	$ 1,393	1,399
2020 | item	1.47
2019 | item	1.81
2018 | item	1.45
2017 | item	2.90
2016 | item	1.60
2015 and prior | item	1.68
Loan-to-value ratio, 75% to 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2016	$ 7
2015 and prior	1
Total	$ 8	$ 1
2016 | item	1.26
2015 and prior | item	0.57