Investments (Impaired Mortgage Loans) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		$ 37	$ 17
Impaired Financing Receivable, Recorded Investment		37	17
Impaired Financing Receivable, Related Allowance		0	0
Impaired Financing Receivable Net Of Related Allowance		37	17
Impaired Financing Receivable, Average Recorded Investment	[1]	25	20	$ 24
Impaired Financing Receivable, Interest Income, Accrual Method		1	1	1
Impaired mortgage loans with no valuation allowance recorded
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		37	17
Impaired Financing Receivable, Recorded Investment		37	17
Impaired Financing Receivable, Related Allowance		0	0
Impaired Financing Receivable Net Of Related Allowance		37	17
Impaired Financing Receivable, Average Recorded Investment	[1]	25	20	24
Impaired Financing Receivable, Interest Income, Accrual Method		1	1	1
Impaired mortgage loans with valuation allowance recorded
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		0	0
Impaired Financing Receivable, Recorded Investment		0	0
Impaired Financing Receivable, Related Allowance		0	0
Impaired Financing Receivable Net Of Related Allowance		0	0
Impaired Financing Receivable, Average Recorded Investment	[1]	0	0	0
Impaired Financing Receivable, Interest Income, Accrual Method		$ 0	$ 0	$ 0

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