Investments (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Gain (Loss) on Securities [Line Items]
Debt securities, available-for-sale, accrued interest, after allowance for credit loss	$ 374,000,000	$ 373,000,000	$ 374,000,000	$ 373,000,000	$ 371,000,000
Mortgage loan losses due to changes in expected credit losses	0	0	0	13,000,000
Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments	2,635,000,000		2,635,000,000		2,773,000,000
Notional value	274,000,000		274,000,000		190,000,000
Derivative liability, fair value, gross liability	(13,000,000)		(13,000,000)		$ (19,000,000)
Commitments to purchase or fund privately placed debt securities	1,330,000,000		1,330,000,000
Commitments to sell various privately placed debt securities	95,000,000		95,000,000
Common Stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	9,000,000	23,000,000	21,000,000	10,000,000
Non-redeemable preferred stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	15,000,000	$ 63,000,000	15,000,000	$ (70,000,000)
Mortgage loans
Gain (Loss) on Securities [Line Items]
Financing receivable, accrued interest, after allowance for credit loss	$ 4,000,000		$ 4,000,000