Investments (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Gain (Loss) on Securities [Line Items]
Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments	$ 2,237,000,000		$ 2,237,000,000		$ 1,078,000,000
Derivative, notional amount	170,000,000		170,000,000		172,000,000
Derivative liability	(9,000,000)		(9,000,000)
Derivative asset, fair value, gross asset					$ 4,000,000
Commitments to purchase or fund privately placed debt securities	865,000,000		865,000,000
Commitments to sell various privately placed debt securities	90,000,000		90,000,000
Common Stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	5,000,000		26,000,000
Preferred stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	7,000,000	$ 2,000,000	60,000,000	$ (23,000,000)
5.875%, face amount of $500, due August 15, 2020
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)		$ 2,000,000	(21,000,000)
Face amount	$ 500,000,000		$ 500,000,000