Closed Block (Revenues and Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues
Premiums	$ 410	$ 432	$ 797	$ 834
Net investment income	431	452	875	918
Net investment gains (losses)	(24)	(2)	(53)	(10)
Net derivative gains (losses)	13	(10)	10	(18)
Total revenues	830	872	1,629	1,724
Expenses
Policyholder benefits and claims	596	614	1,167	1,182
Policyholder dividends	238	247	482	497
Other expenses	30	32	59	64
Total expenses	864	893	1,708	1,743
Revenues, net of expenses before provision for income tax expense (benefit)	(34)	(21)	(79)	(19)
Provision for income tax expense (benefit)	(7)	(8)	(17)	(8)
Revenues, net of expenses and provision for income tax expense (benefit)	$ (27)	$ (13)	$ (62)	$ (11)