Schedule I - Summary Of Investments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Cost	$ 3,575
Investments	3,792	$ 3,937
Other Investments and Securities, at Cost	388
Other Investments	478	$ 391
U.S. Government Obligations [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities	156
Short-term Investments [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	737
Available-for-sale Securities	737
U S Government Obligations [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Cost	157
Fixed Income Securities [Member] \| Municipal Bonds [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	194
Available-for-sale Securities	215
Fixed Income Securities [Member] \| Corporate Debt Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,396
Available-for-sale Securities	1,430
Fixed Income Securities [Member] \| Debt Security, Government, Non-US [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	44
Available-for-sale Securities	44
Fixed Income Securities [Member] \| Residential Mortgage-Backed Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	200
Available-for-sale Securities	248
Fixed Income Securities [Member] \| Collateralized Mortgage Backed Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	49
Available-for-sale Securities	50
Fixed Income Securities [Member] \| Collateralized Debt Obligations [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	147
Available-for-sale Securities	146
Fixed Income Securities [Member] \| Asset-backed Securities [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Available-for-sale Securities, Amortized Cost Basis	263
Available-for-sale Securities	287
Fair Value Measurement [Domain]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Investments	3,807
Other Investments	$ 493

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