FAIR VALUE OF FINANCIAL INSTRUMENTS - Determination of Fair Values Additional Information (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) primary_source quote	Dec. 31, 2015 USD ($)	Jan. 31, 2015 USD ($)
Determination of fair values
Number of primary sources of information used for determining fair value | primary_source	1
Total number of primary sources of information available for determining fair value | primary_source	3
Minimum percentage of the Company's fixed maturity securities priced by third party pricing services	90.00%
Number of independent non-binding broker quotes obtained per security | quote	1
Minimum percentage of underlying collateral guaranteed by third party	97.00%
Embedded derivative - GLWB | Level 3
Determination of fair values
Discount rate curve, base rate	LIBOR
Embedded derivative - GLWB | Level 3 | Minimum
Determination of fair values
Mortality (as a percent)	91.10%
Embedded derivative - GLWB | Level 3 | Maximum
Determination of fair values
Mortality (as a percent)	106.60%
Embedded derivative - FIA | Level 3 | Annuity account
Determination of fair values
Discount rate curve, base rate	LIBOR
Embedded derivative - FIA | Level 3 | Annuity account | Minimum
Determination of fair values
Mortality (as a percent)	46.00%
Embedded derivative - FIA | Level 3 | Annuity account | Maximum
Determination of fair values
Mortality (as a percent)	113.00%
Embedded derivative - IUL | Level 3
Determination of fair values
Discount rate curve, base rate	LIBOR
Embedded derivative - IUL | Level 3 | Minimum
Determination of fair values
Mortality (as a percent)	38.00%
Embedded derivative - IUL | Level 3 | Maximum
Determination of fair values
Mortality (as a percent)	153.00%
Successor
Determination of fair values
Transfers from Level 1 to Level 2	$ 100,000	$ 21,000,000
Percentage of derivatives excluding embedded derivatives that were priced using exchange prices or independent broker quotations	79.00%
Statutory policy liabilities (net of policy loans)	$ 674,048,000	522,225,000
Other long-term investments	533,433,000	323,570,000
Successor | Interest support, YRT premium support and portfolio maintenance agreement
Determination of fair values
Other long-term investments	48,900,000
Successor | Golden Gate II Captive Insurance Company (Golden Gate II) | Interest Support Agreement
Determination of fair values
Interest support agreement, amount collateralized	1,500,000
Payments triggered under agreement	0
Other long-term investments	43,300,000
Successor | Golden Gate II Captive Insurance Company (Golden Gate II) | YRT premium support agreement
Determination of fair values
Payments triggered under agreement	0
Other long-term investments	2,000,000
Successor | Golden Gate V and West Coast Life | Portfolio maintenance agreements
Determination of fair values
Payments triggered under agreement	0
Other long-term investments	3,600,000
Successor | Other long-term investments
Determination of fair values
Transfers from Level 1 to Level 2	169,400,000
Successor | Other liabilities
Determination of fair values
Transfers from Level 1 to Level 2	120,000,000
Successor | Level 3
Determination of fair values
Financial instruments that are valued using broker quotes	125,200,000
Financial instruments with book value approximating to fair value	65,700,000
Successor | Level 3 | Annuity account
Determination of fair values
Statutory policy liabilities (net of policy loans)		92,512,000
Successor | Asset-Backed Securities | Level 2
Determination of fair values
Fair value, assets	4,800,000,000
Successor | Asset-Backed Securities | Level 3
Determination of fair values
Fair value, assets	647,200,000
Successor | Other asset-backed securities | Level 3
Determination of fair values
Fair value, assets	553,308,000	587,031,000
Financial instruments that are valued using broker quotes	93,900,000
Successor | Other asset-backed securities | Level 3 | Available-for-sale securities
Determination of fair values
Fair value, assets	562,600,000
Successor | Other asset-backed securities | Level 3 | Trading securities
Determination of fair values
Fair value, assets	$ 84,600,000
Minimum percentage of underlying collateral guaranteed by third party	97.00%
Successor | Corporate Bonds, U.S. Government-Related Securities, States, Municipals, and Political Subdivisions, and Other Government Related Securities | Level 2
Determination of fair values
Fair value, assets	$ 30,700,000,000
Successor | Corporate Bonds, U.S. Government-Related Securities, States, Municipals, and Political Subdivisions, and Other Government Related Securities | Level 3
Determination of fair values
Fair value, assets	669,500,000
Successor | Equity securities | Level 2 and Level 3
Determination of fair values
Fair value, assets	65,800,000
Federal home loan bank stock	65,700,000
Successor | Embedded derivative - GLWB
Determination of fair values
Statutory policy liabilities (net of policy loans)	2,400,000,000
Unrealized gain (loss) of securities	147,300,000
Successor | Embedded derivative - GLWB | Level 3
Determination of fair values
Statutory policy liabilities (net of policy loans)	7,031,000	18,511,000
Successor | Corporate securities | Level 3
Determination of fair values
Fair value, assets	638,279,000	875,810,000
Financial instruments that are valued using broker quotes	31,300,000
Successor | Embedded derivative - FIA | Level 3
Determination of fair values
Statutory policy liabilities (net of policy loans)	147,368,000	100,329,000
Successor | Embedded derivative - IUL | Level 3
Determination of fair values
Statutory policy liabilities (net of policy loans)	46,051,000
Successor | Funds withheld derivative | Level 2
Determination of fair values
Fair value, derivative liability	91,300,000
Predecessor
Determination of fair values
Transfers from Level 1 to Level 2			$ 0
Predecessor | Level 3
Determination of fair values
Financial instruments that are valued using broker quotes		197,500,000
Financial instruments with book value approximating to fair value		66,500,000
Predecessor | Other asset-backed securities | Level 3
Determination of fair values
Financial instruments that are valued using broker quotes		152,900,000
Predecessor | Corporate securities | Level 3
Determination of fair values
Financial instruments that are valued using broker quotes		44,600,000
Predecessor | Embedded derivative - IUL | Level 3
Determination of fair values
Statutory policy liabilities (net of policy loans)		29,629,000
Measured at fair value on a recurring basis | Successor | Level 2
Determination of fair values
Fair value, assets	35,922,155,000	32,669,641,000
Other long-term investments	335,497,000	141,487,000
Fair value, derivative liability	255,241,000	106,310,000
Measured at fair value on a recurring basis | Successor | Level 3
Determination of fair values
Fair value, assets	1,498,010,000	1,795,178,000
Other long-term investments	115,516,000	68,384,000
Fair value, derivative liability	405,803,000	375,848,000
Annuity account balances	$ 87,616,000	$ 92,512,000