Reinsurance - Effect of Reinsurance on Premiums Earned, Benefits Incurred and Reserve Changes (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Benefits and Other Changes in Insurance Policy Reserves:
Net	$ 297		$ 475
Traditional life insurance premiums
Premiums and other considerations:
Direct	54		172
Assumed	0		0
Ceded	(42)		(127)
Net	12		45
Benefits and Other Changes in Insurance Policy Reserves:
Direct	336		653
Assumed	12		(14)
Ceded	(51)		(164)
Net	$ 297		$ 475
Predecessor
Benefits and Other Changes in Insurance Policy Reserves:
Net		$ 320		$ 823
Predecessor | Traditional life insurance premiums
Premiums and other considerations:
Direct		58		176
Assumed		0		0
Ceded		(42)		(145)
Net		16		31
Benefits and Other Changes in Insurance Policy Reserves:
Direct		389		1,028
Assumed		0		0
Ceded		(69)		(205)
Net		$ 320		$ 823