OFFSETTING OF ASSETS AND LIABILITIES - Offsetting of Derivative Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Offsetting of Derivative Assets
Other long-term investments	$ 995,493	$ 414,827
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	995,493	414,827
Gross Amounts Not Offset in the statement of Financial Position, Financial Instruments, subject to master netting arrangement	452,562	70,322
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	215,587	99,199
Net Amount	327,344	245,306
Free-Standing derivatives
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets, subject to master netting arrangement	785,650	263,349
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	785,650	263,349
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments, not subject to master netting arrangement	452,562	70,322
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	215,587	99,199
Net Amount	117,501	93,828
Total derivatives, subject to a master netting arrangement or similar arrangement
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets, subject to master netting arrangement	785,650	263,349
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	785,650	263,349
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments, not subject to master netting arrangement	452,562	70,322
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	215,587	99,199
Net Amount	117,501	93,828
Embedded derivative - Modco reinsurance treaties
Offsetting of Derivative Assets
Other long-term investments	31,926	7,072
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	31,926	7,072
Gross Amounts Not Offset in the statement of Financial Position, Financial Instruments, subject to master netting arrangement	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	31,926	7,072
Embedded derivative - GLWB
Offsetting of Derivative Assets
Other long-term investments	62,538	54,221
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	62,538	54,221
Gross Amounts Not Offset in the statement of Financial Position, Financial Instruments, subject to master netting arrangement	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	62,538	54,221
Derivatives with PLC
Offsetting of Derivative Assets
Other long-term investments	115,379	90,049
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	115,379	90,049
Gross Amounts Not Offset in the statement of Financial Position, Financial Instruments, subject to master netting arrangement	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	115,379	90,049
Other
Offsetting of Derivative Assets
Other long-term investments	0	136
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	0	136
Gross Amounts Not Offset in the statement of Financial Position, Financial Instruments, subject to master netting arrangement	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	0	136
Total derivatives, not subject to a master netting arrangement or similar arrangement
Offsetting of Derivative Assets
Other long-term investments	209,843	151,478
Gross Amounts Offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position, Including not subject to master netting arrangement	209,843	151,478
Gross Amounts Not Offset in the statement of Financial Position, Financial Instruments, subject to master netting arrangement	0	0
Gross Amounts Not Offset in the Statement of Financial Position, Collateral Received	0	0
Net Amount	$ 209,843	$ 151,478

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