Investments (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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	$ 1,816,000,000		$ 1,816,000,000		$ 1,078,000,000
Derivative, notional amount	172,000,000		172,000,000		172,000,000
Derivative liability	(8,000,000)		(8,000,000)
Derivative asset, fair value, gross asset					$ 4,000,000
Commitments to purchase or fund privately placed debt securities	875,000,000		875,000,000
Commitments to sell various privately placed debt securities	85,000,000		85,000,000
Common Stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	4,000,000	$ 2,000,000	21,000,000	$ 1,000,000
Preferred stock
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	11,000,000	$ (10,000,000)	(53,000,000)	$ (25,000,000)
5.875%, face amount of $500, due August 15, 2020
Gain (Loss) on Securities [Line Items]
Equity securities, FV-NI, gain (loss)	(21,000,000)		(21,000,000)
Face amount	$ 500,000,000		$ 500,000,000