Investments (Commercial Mortgage Loans By Year Of Origination) (Details) - Commercial [Member] $ in Millions	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 1,536
2019	3,401
2018	2,583
2017	1,955
2016	1,909
2015 and prior	4,851
Total	16,235	$ 15,606
Loan-to-value ratio, less than 65% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,504
2019	3,141
2018	2,382
2017	1,786
2016	1,713
2015 and prior	4,710
Total	$ 15,236	14,206
2020 | item	2.86
2019 | item	2.25
2018 | item	2.16
2017 | item	2.34
2016 | item	2.37
2015 and prior | item	2.38
Loan-to-value ratio, 65% to 74% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 32
2019	258
2018	186
2017	169
2016	174
2015 and prior	133
Total	$ 952	1,399
2020 | item	1.52
2019 | item	1.78
2018 | item	1.49
2017 | item	1.73
2016 | item	1.56
2015 and prior | item	1.95
Loan-to-value ratio, 75% to 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2019	$ 2
2018	15
2016	22
2015 and prior	8
Total	$ 47	$ 1
2019 | item	1.74
2018 | item	0.71
2016 | item	1.58
2015 and prior | item	1.02