OFFSETTING OF ASSETS AND LIABILITIES - Offsetting of Derivative Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	$ 605,075	$ 542,243
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	605,075	542,243
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	242,105	171,384
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	108,830	100,890
Net Amount	254,140	269,969
Derivatives not subject to a master netting arrangement or similar arrangement
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	468,871	417,769
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	468,871	417,769
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	242,105	171,384
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	108,830	100,890
Net Amount	117,936	145,495
Free-Standing derivatives
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	468,871	417,769
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	468,871	417,769
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	242,105	171,384
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	108,830	100,890
Net Amount	117,936	145,495
Total derivatives, not subject to a master netting arrangement or similar arrangement
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	136,204	124,474
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	136,204	124,474
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	136,204	124,474
Embedded derivative - Modco reinsurance treaties
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	1,009	2,573
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	1,009	2,573
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	1,009	2,573
Embedded derivative - GLWB
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	134,995	121,752
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	134,995	121,752
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	134,995	121,752
Other
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	200	149
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	200	149
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	$ 200	$ 149

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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