Investments (Mortgage Loans by Maturity Date) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Document Period End Date	Jun. 30, 2021
Loans Receivable, Gross, Commercial, Real Estate	$ 6,537	$ 5,861
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%	100.00%
Due within five years
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 2,585	$ 2,276
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	39.60%	38.80%
Due after five years through ten years
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 2,845	$ 2,768
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	43.50%	47.30%
Due after ten years
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans Receivable, Gross, Commercial, Real Estate	$ 1,107	$ 817
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	16.90%	13.90%