Investments (Impaired Mortgage Loans) (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019	Dec. 31, 2019
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		$ 37			$ 37			$ 17
Recorded Investment		37			37			17
Related Allowance		0			0			0
Carrying Value		37			37			17
Average Investment	[1]	27		$ 17	22		$ 20
Interest Income		0		1	0		1
Impaired mortgage loans with valuation allowance recorded
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		0			0			0
Recorded Investment		0			0			0
Related Allowance		0			0			0
Carrying Value		0			0			0
Average Investment		0		0			0
Interest Income		0		0	0		0
Impaired mortgage loans with no valuation allowance recorded
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance		37			37			17
Recorded Investment		37			37			17
Related Allowance		0			0			0
Carrying Value		37			37			$ 17
Average Investment		27	[1]	17	22	[1]	20
Interest Income		$ 0		$ 1	$ 0		$ 1

[1] Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances.