Derivatives - Narrative (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) swap	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Carrying value of collateral received to support purchased call options	$ 406,000,000		$ 103,000,000
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	16
Notional amount of derivative instrument outstanding	$ 2,310,000,000.00		2,350,000,000.00
Gain (loss) reclassified from AOCI into net investment income	(2,000,000)	$ 1,000,000
Gain (loss) on cash flow hedge ineffectiveness recorded in Net Earnings	0	$ 0
Collateral receivable supporting interest rate swaps	134,000,000		135,000,000
Other assets | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value	25,000,000		16,000,000
Other liabilities | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value	$ (25,000,000)		$ (46,000,000)