Derivative Financial Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Total asset derivatives	$ 449
Total liability derivatives	2,573
Call options | Derivative Instruments
Derivative [Line Items]
Total asset derivatives	431
Futures contracts | Derivative Instruments
Derivative [Line Items]
Total asset derivatives	0
Foreign Exchange Forward [Member] | Derivative Instruments
Derivative [Line Items]
Total asset derivatives	1
Other derivatives and embedded derivatives | Other invested assets
Derivative [Line Items]
Total asset derivatives	17
FIA embedded derivative | Contractholder funds
Derivative [Line Items]
Total liability derivatives	2,551
Preferred shares reimbursement feature embedded derivative | Other Liabilities [Member]
Derivative [Line Items]
Total liability derivatives	$ 22
Predecessor
Derivative [Line Items]
Total asset derivatives		$ 509
Total liability derivatives		2,300
Predecessor | Call options | Derivative Instruments
Derivative [Line Items]
Total asset derivatives		492
Predecessor | Futures contracts | Derivative Instruments
Derivative [Line Items]
Total asset derivatives		0
Predecessor | Foreign Exchange Forward [Member]
Derivative [Line Items]
Total asset derivatives		0
Predecessor | Other derivatives and embedded derivatives | Other invested assets
Derivative [Line Items]
Total asset derivatives		17
Predecessor | FIA embedded derivative | Contractholder funds
Derivative [Line Items]
Total liability derivatives		2,277
Predecessor | Preferred shares reimbursement feature embedded derivative | Other Liabilities [Member]
Derivative [Line Items]
Total liability derivatives		$ 23