OFFSETTING OF ASSETS AND LIABILITIES - Schedule of Derivative Instruments by Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Derivative instruments by assets
Fair value of non-cash collateral	$ 39,900	$ 21,300
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives Not Subject to a master netting arrangement	1,172,964	995,493
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	1,172,964	995,493
Gross Amounts Not Offset in the statement of Financial Position, Financial Instruments, subject to master netting arrangement	328,282	452,562
Gross Amounts Not Offset in the Statement of Financial Position, Cash collateral received	404,541	215,587
Net Amount	440,141	327,344
Free-Standing derivatives
Offsetting of Assets
Gross Amounts of Recognized Assets, subject to master netting arrangement	897,057	785,650
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	897,057	785,650
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments, not subject to master netting arrangement	328,282	452,562
Gross Amounts Not Offset in the Statement of Financial Position, Cash collateral received	404,541	215,587
Net Amount	164,234	117,501
Total derivatives, subject to a master netting arrangement or similar arrangement
Offsetting of Assets
Gross Amounts of Recognized Assets, subject to master netting arrangement	897,057	785,650
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	897,057	785,650
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments, not subject to master netting arrangement	328,282	452,562
Gross Amounts Not Offset in the Statement of Financial Position, Cash collateral received	404,541	215,587
Net Amount	164,234	117,501
Embedded derivative - Modco reinsurance treaties
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives Not Subject to a master netting arrangement	64,758	31,926
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	64,758	31,926
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, Cash collateral received	0	0
Net Amount	64,758	31,926
Embedded derivative - GLWB
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives Not Subject to a master netting arrangement	45,636	62,538
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	45,636	62,538
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, Cash collateral received	0	0
Net Amount	45,636	62,538
Derivatives with PLC
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives Not Subject to a master netting arrangement	113,653	115,379
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	113,653	115,379
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, Cash collateral received	0	0
Net Amount	113,653	115,379
Other
Offsetting of Assets
Gross Amounts of Recognized Assets, Derivatives Not Subject to a master netting arrangement	51,860	0
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	51,860	0
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, Cash collateral received	0	0
Net Amount	51,860	0
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	275,907	209,843
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts of Assets Presented in the Balance Sheets	275,907	209,843
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, Cash collateral received	0	0
Net Amount	$ 275,907	$ 209,843

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