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	$ 949
2019	3,406
2018	2,600
2017	1,980
2016	1,935
2015 and prior	5,120
Total	15,990	$ 15,511
Loan-to-value ratio, less than 65% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	890
2019	2,890
2018	2,340
2017	1,808
2016	1,712
2015 and prior	4,959
Total	$ 14,599	14,121
2020 | item	3.27
2019 | item	2.29
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	516
2018	260
2017	172
2016	216
2015 and prior	160
Total	$ 1,383	1,389
2020 | item	1.47
2019 | item	1.81
2018 | item	1.45
2017 | item	2.90
2016 | item	1.60
2015 and prior | item	1.72
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