Investments (Credit Losses Recognized In Earnings on Fixed Maturity Securities Held by the Company) (Details) - Fixed maturities $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Available-for-sale
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	$ 0
Additions to allowance for credit losses not previously recorded	158
Balance, ending of period	158
Available-for-sale | U.S. Treasury securities and obligations of U.S. government authorities and agencies
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Additions to allowance for credit losses not previously recorded	0
Balance, ending of period	0
Available-for-sale | Foreign government bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Additions to allowance for credit losses not previously recorded	38
Balance, ending of period	38
Available-for-sale | U.S. and Foreign Corporate Securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Additions to allowance for credit losses not previously recorded	119
Balance, ending of period	119
Available-for-sale | Asset-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Additions to allowance for credit losses not previously recorded	0
Balance, ending of period	0
Available-for-sale | Commercial mortgage-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Additions to allowance for credit losses not previously recorded	1
Balance, ending of period	1
Available-for-sale | Residential mortgage-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Additions to allowance for credit losses not previously recorded	0
Balance, ending of period	0
Held-to-maturity
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Cumulative effect of adoption of ASU 2016-13	9
Balance, ending of period	9
Held-to-maturity | U.S. Treasury securities and obligations of U.S. government authorities and agencies
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Cumulative effect of adoption of ASU 2016-13	0
Balance, ending of period	0
Held-to-maturity | Foreign government bonds
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Cumulative effect of adoption of ASU 2016-13	0
Balance, ending of period	0
Held-to-maturity | U.S. and Foreign Corporate Securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Cumulative effect of adoption of ASU 2016-13	9
Balance, ending of period	9
Held-to-maturity | Asset-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Cumulative effect of adoption of ASU 2016-13	0
Balance, ending of period	0
Held-to-maturity | Commercial mortgage-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Cumulative effect of adoption of ASU 2016-13	0
Balance, ending of period	0
Held-to-maturity | Residential mortgage-backed securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Balance, beginning of period	0
Cumulative effect of adoption of ASU 2016-13	0
Balance, ending of period	$ 0