Investments (Mortgage Loans by Credit Quality Indicator) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 6,040	$ 5,727
Loans Receivable, Gross, Commercial, Construction	$ 1	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
LTV 0 to 59 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 3,198	$ 3,084
Loans Receivable, Gross, Commercial, Construction	$ 1	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	53.00%	53.80%
LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 2,031	$ 1,905
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	33.60%	33.30%
LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 623	$ 544
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	10.30%	9.50%
Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 188	$ 194
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	3.10%	3.40%
Debt Service Coverage Ratio Range One [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 5,657	$ 5,454
Debt Service Coverage Ratio Range One [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	3,074	3,025
Debt Service Coverage Ratio Range One [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,923	1,841
Debt Service Coverage Ratio Range One [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	559	492
Debt Service Coverage Ratio Range One [Member] | Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	101	96
Debt Service Coverage Ratio Range Two [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	313	179
Debt Service Coverage Ratio Range Two [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	114	52
Debt Service Coverage Ratio Range Two [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	78	53
Debt Service Coverage Ratio Range Two [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	60	13
Debt Service Coverage Ratio Range Two [Member] | Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	61	61
Debt Service Coverage Ratio Range Three [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	69	94
Debt Service Coverage Ratio Range Three [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	9	7
Debt Service Coverage Ratio Range Three [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	30	11
Debt Service Coverage Ratio Range Three [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	4	39
Debt Service Coverage Ratio Range Three [Member] | Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 26	$ 37