Derivative Financial Instruments and Off-balance sheet Financial Instruments - Foreign currency contracts in cash flow hedging and other (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss)
Hedge ineffectiveness in realized gains	$ 0	$ 0	$ 0
Gain (loss) recognized in OCI on derivatives during the period	1,000,000	(2,000,000)	(1,000,000)
Gain recognized in OCI on derivatives during the term of the hedging relationship	0	2,000,000	5,000,000
Total gain (loss) recognized in net income on derivatives	45,000,000	33,000,000	33,000,000
Net investment income | Reclassification out of Accumulated Other Comprehensive Income | Cash flow hedges
Derivative Instruments, Gain (Loss)
Investment income, net	0	1,000,000	1,000,000
Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Total gain (loss) recognized in net income on derivatives	7,000,000	(16,000,000)	5,000,000
Realized capital gains and losses | Reclassification out of Accumulated Other Comprehensive Income | Cash flow hedges
Derivative Instruments, Gain (Loss)
Investment income, net	3,000,000	0	3,000,000
Contract benefits
Derivative Instruments, Gain (Loss)
Total gain (loss) recognized in net income on derivatives	(5,000,000)	9,000,000	9,000,000
Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Total gain (loss) recognized in net income on derivatives	43,000,000	40,000,000	19,000,000
Interest rate contracts
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	1,000,000
Interest rate contracts | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	1,000,000
Interest rate contracts | Contract benefits
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0
Interest rate contracts | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0
Equity and index contracts
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(27,000,000)	41,000,000	14,000,000
Equity and index contracts | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(4,000,000)	(4,000,000)	(4,000,000)
Equity and index contracts | Contract benefits
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0	0	0
Equity and index contracts | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(23,000,000)	45,000,000	18,000,000
Embedded derivative financial instruments
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	61,000,000	4,000,000	10,000,000
Embedded derivative financial instruments | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0	0	0
Embedded derivative financial instruments | Contract benefits
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(5,000,000)	9,000,000	9,000,000
Embedded derivative financial instruments | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	66,000,000	(5,000,000)	1,000,000
Foreign currency contracts
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	12,000,000	(14,000,000)	6,000,000
Foreign currency contracts | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	12,000,000	(14,000,000)	6,000,000
Foreign currency contracts | Contract benefits
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0	0	0
Foreign currency contracts | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0	0	0
Credit default swaps
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		2,000,000	3,000,000
Credit default swaps | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		2,000,000	3,000,000
Credit default swaps | Contract benefits
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		0	0
Credit default swaps | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives		$ 0	$ 0
Total return swaps - fixed income
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(1,000,000)
Total return swaps - fixed income | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(1,000,000)
Total return swaps - fixed income | Life and Annuity Contract Benefits [Member]
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0
Total return swaps - fixed income | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0
Total return swaps - equity
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(1,000,000)
Total return swaps - equity | Realized capital gains and losses
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(1,000,000)
Total return swaps - equity | Life and Annuity Contract Benefits [Member]
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	0
Total return swaps - equity | Interest credited to contractholder funds
Derivative Instruments, Gain (Loss)
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	$ 0