Derivatives - Narrative (Details)	3 Months Ended			6 Months Ended
	Jun. 30, 2018 USD ($) swap	Mar. 31, 2018 USD ($) swap	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) swap	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Carrying value of collateral received to support purchased call options	$ 353,000,000			$ 353,000,000		$ 389,000,000
Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate swaps designated and qualifying as a cash flow hedges | swap	11			11
Notional amount of derivative instrument outstanding	$ 1,639,000,000			$ 1,639,000,000		1,580,000,000
Gain (loss) reclassified from AOCI into net investment income	(2,000,000)		$ 1,000,000	(1,000,000)	$ 3,000,000
Gain (loss) on cash flow hedge ineffectiveness recorded in Net Earnings	0		$ 0	0	$ 0
Collateral receivable supporting interest rate swaps	116,000,000			116,000,000		70,000,000
Other assets | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value	0			0
Other assets | Maximum | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value						1,000,000
Other liabilities | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value	(70,000,000)			(70,000,000)		$ (31,000,000)
New interest rate swaps entered into during the period | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instrument outstanding		$ 130,000,000
Number of interest rate swaps entered into during the period | swap		1
Annuity benefits | Not Designated as Hedging Instrument | Fixed-Indexed Annuities (Embedded Derivative) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total realized/unrealized gains (losses) included in net income for the embedded derivatives related to the unlocking of actuarial assumptions	$ (44,000,000)			$ (44,000,000)