OFFSETTING OF ASSETS AND LIABILITIES - Schedule of Derivative Instruments by Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives not subject to a master netting arrangement	$ 586,765	$ 605,075
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	586,765	605,075
Derivative Asset, Not Offset, Policy Election Deduction	194,876	242,105
Gross Amounts Not Offset in the Statement of Financial Position, Cash/Securities Received as Collateral	126,320	108,830
Net Amount	265,569	254,140
Free-Standing derivatives
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives	442,253	468,871
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	442,253	468,871
Derivative Asset, Not Subject to Master Netting Arrangement Deduction	194,876	242,105
Gross Amounts Not Offset in the Statement of Financial Position, Cash/Securities Received as Collateral	126,320	108,830
Net Amount	121,057	117,936
Total derivatives, subject to a master netting arrangement or similar arrangement
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives	442,253	468,871
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	442,253	468,871
Derivative Asset, Not Subject to Master Netting Arrangement Deduction	194,876	242,105
Gross Amounts Not Offset in the Statement of Financial Position, Cash/Securities Received as Collateral	126,320	108,830
Net Amount	121,057	117,936
Embedded derivative - Modco reinsurance treaties
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives not subject to a master netting arrangement	497	1,009
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	497	1,009
Derivative Asset, Not Offset, Policy Election Deduction	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Cash/Securities Received as Collateral	0	0
Net Amount	497	1,009
Embedded derivative - GLWB
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives not subject to a master netting arrangement	143,855	134,995
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	143,855	134,995
Derivative Asset, Not Offset, Policy Election Deduction	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Cash/Securities Received as Collateral	0	0
Net Amount	143,855	134,995
Other
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives not subject to a master netting arrangement	160	200
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	160	200
Derivative Asset, Not Offset, Policy Election Deduction	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Cash/Securities Received as Collateral	0	0
Net Amount	160	200
Total derivatives, not subject to a master netting arrangement or similar arrangement
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives not subject to a master netting arrangement	144,512	136,204
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	144,512	136,204
Derivative Asset, Not Offset, Policy Election Deduction	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Cash/Securities Received as Collateral	0	0
Net Amount	$ 144,512	$ 136,204

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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