Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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The amount of loss reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

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Level 4~Derivatives - Cash Flow Hedges (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Collateral, Obligation to Return Cash	$ 1,000,000		$ 1,000,000
AOCI, net of tax
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net reclassifications from AOCI to earnings resulting from the discontinuance of cash-flow hedges due to forecasted transactions that were no longer probable of occurring	0	$ 0
Cash Flow Hedging \| Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(21,000,000)	(3,000,000)
Cash Flow Hedging \| Designated as Hedging Instrument \| Reclassification out of Accumulated Other Comprehensive Income
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	9,000,000	13,000,000
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(14,000,000)	(3,000,000)
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest Rate Swap [Member] \| Reclassification out of Accumulated Other Comprehensive Income \| Net realized capital gain/(loss)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	1,000,000
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest Rate Swap [Member] \| Reclassification out of Accumulated Other Comprehensive Income \| Net investment income
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	8,000,000
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest Rate Swap [Member] \| Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent \| Net realized capital gain/(loss)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)		4,000,000
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest Rate Swap [Member] \| Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent \| Net investment income
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)		$ 9,000,000
Cash Flow Hedging \| Designated as Hedging Instrument \| Foreign currency swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ (7,000,000)