Investments (Mortgage Loans by Credit Quality Indicator) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 6,537	$ 5,861
Loans Receivable, Gross, Commercial, Construction	$ 24	$ 12
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]
Loans Receivable, Gross, Commercial, Real Estate	$ 3,416	$ 2,909
Loans Receivable, Gross, Commercial, Construction	$ 24	$ 12
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	52.20%	49.60%
LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 2,352	$ 2,108
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	36.00%	36.00%
LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 555	$ 617
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	8.50%	10.50%
Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 214	$ 227
Loans Receivable, Gross, Commercial, Construction	$ 0	$ 0
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	3.30%	3.90%
Debt Service Coverage Ratio Range One [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 5,859	$ 5,531
Debt Service Coverage Ratio Range One [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	3,053	2,774
Debt Service Coverage Ratio Range One [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	2,110	2,013
Debt Service Coverage Ratio Range One [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	503	555
Debt Service Coverage Ratio Range One [Member] | Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	193	189
Debt Service Coverage Ratio Range Two [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	510	238
Debt Service Coverage Ratio Range Two [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	274	106
Debt Service Coverage Ratio Range Two [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	200	62
Debt Service Coverage Ratio Range Two [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	36	49
Debt Service Coverage Ratio Range Two [Member] | Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	0	21
Debt Service Coverage Ratio Range Three [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	144	80
Debt Service Coverage Ratio Range Three [Member] | LTV 0 to 59 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	65	17
Debt Service Coverage Ratio Range Three [Member] | LTV 60 To 69 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	42	33
Debt Service Coverage Ratio Range Three [Member] | LTV 70 To 79 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	16	13
Debt Service Coverage Ratio Range Three [Member] | Debt-to-Value Ratio, 80 to 100 Percent [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 21	$ 17