Derivatives - Narrative (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) swap	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Carrying value of collateral received to support purchased call options	$ 76,000,000		$ 577,000,000
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	12
Derivative, notional amount	$ 1,860,000,000		1,980,000,000
Gain (loss) reclassified from AOCI into net investment income	12,000,000	$ (2,000,000)
Collateral payable related to interest rate swaps	19,000,000
Collateral receivable related to interest rate swaps			20,000,000
Other assets | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value	125,000,000		50,000,000
Other liabilities | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value			$ (5,000,000)
Contract termination | Cash Flow Hedges | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	$ 83,000,000
Number of interest rate derivatives terminated | swap	1
Maximum | Other liabilities | Cash Flow Hedges | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value	$ (1,000,000)