Derivative Financial Instruments - Schedule of Change in Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	$ (3)		$ (37)
Change In Fair Value Of Derivatives	159	$ 111	58
Call options | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	153	113	86
Futures contracts | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	8		8
Foreign Exchange Forward [Member] | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	1	0	1
Other derivatives and embedded derivatives | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	0	1	0
Reinsurance related embedded derivative | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	(3)	(8)	(37)
Preferred shares reimbursement feature embedded derivative | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	2	0	1
FIA embedded derivative
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives	$ 231	185	$ 274
Predecessor
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives		(8)		$ (28)
Change In Fair Value Of Derivatives				284
Predecessor | Call options | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives				299
Predecessor | Futures contracts | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives		$ 5		10
Predecessor | Foreign Exchange Forward [Member] | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives				0
Predecessor | Other derivatives and embedded derivatives | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives				3
Predecessor | Reinsurance related embedded derivative | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives				(28)
Predecessor | Preferred shares reimbursement feature embedded derivative | Net investment (losses) gains
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives				0
Predecessor | FIA embedded derivative
Derivative [Line Items]
Change in fair value of reinsurance related embedded derivatives				$ 377