FAIR VALUE OF FINANCIAL INSTRUMENTS - Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2015
Successor
Assets:
Available-for-sale securities, fair value	$ 36,570,665,000	$ 33,847,196,000
Total fixed maturity securities	38,183,337,000	35,573,250,000
Equity securities	754,489,000	739,263,000
Other long-term investments	542,243,000	352,016,000
Short-term investments	332,431,000	268,718,000
Assets related to separate accounts
Variable annuity	13,244,252,000	12,829,188,000
Variable universal life	895,925,000	827,610,000
Liabilities:
Transfers from Level 1 to Level 2	100,000
Successor | Other liabilities
Liabilities:
Transfers from Level 1 to Level 2	120,000,000
Successor | Other long-term investments
Liabilities:
Transfers from Level 1 to Level 2	169,400,000
Successor | Fixed maturities
Assets:
Available-for-sale securities, fair value	35,543,477,000	32,909,201,000
Trading securities	2,600,000,000	2,700,000,000
Successor | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value	1,898,483,000	1,765,273,000
Successor | Commercial mortgage-backed securities
Assets:
Available-for-sale securities, fair value	1,811,470,000	1,286,887,000
Successor | Other asset-backed securities
Assets:
Available-for-sale securities, fair value	1,211,533,000	797,051,000
Successor | States, municipals, and political subdivisions
Assets:
Available-for-sale securities, fair value	1,656,503,000	1,603,600,000
Successor | Other government-related securities
Assets:
Available-for-sale securities, fair value	239,921,000	17,740,000
Successor | Corporate securities
Assets:
Available-for-sale securities, fair value	27,371,565,000	25,843,786,000
Successor | Preferred stock
Assets:
Available-for-sale securities, fair value	85,843,000	62,687,000
Successor | Level 3 | Other asset-backed securities
Assets:
Total investments	553,308,000
Successor | Level 3 | Corporate securities
Assets:
Total investments	638,279,000
Successor | Measured at fair value on a recurring basis | Other liabilities
Liabilities:
Transfers from Level 1 to Level 2	120,000,000
Successor | Measured at fair value on a recurring basis | Other long-term investments
Liabilities:
Transfers from Level 1 to Level 2	169,400,000
Successor | Measured at fair value on a recurring basis | Level 1
Assets:
Total fixed maturity securities	1,095,210,000
Equity securities	685,443,000
Other long-term investments	82,420,000
Short-term investments	328,829,000
Total investments	2,191,902,000
Cash	348,182,000
Other assets	23,830,000
Assets related to separate accounts
Variable annuity	13,244,252,000
Variable universal life	895,925,000
Total assets measured at fair value on a recurring basis	16,704,091,000
Liabilities:
Other liabilities	13,004,000
Total liabilities measured at fair value on a recurring basis	13,004,000
Successor | Measured at fair value on a recurring basis | Level 1 | Fixed maturities
Assets:
Available-for-sale securities, fair value	1,068,801,000
Trading securities	26,409,000
Successor | Measured at fair value on a recurring basis | Level 1 | U.S. government-related securities
Assets:
Available-for-sale securities, fair value	1,002,020,000
Trading securities	22,424,000
Successor | Measured at fair value on a recurring basis | Level 1 | Preferred stock
Assets:
Available-for-sale securities, fair value	66,781,000
Trading securities	3,985,000
Successor | Measured at fair value on a recurring basis | Level 2
Assets:
Total fixed maturity securities	35,771,419,000
Equity securities	36,000
Other long-term investments	335,498,000
Short-term investments	3,602,000
Total investments	36,110,555,000
Assets related to separate accounts
Total assets measured at fair value on a recurring basis	36,110,555,000
Liabilities:
Other liabilities	163,974,000
Total liabilities measured at fair value on a recurring basis	163,974,000
Successor | Measured at fair value on a recurring basis | Level 2 | Fixed maturities
Assets:
Available-for-sale securities, fair value	33,248,023,000
Trading securities	2,523,396,000
Successor | Measured at fair value on a recurring basis | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value	1,898,480,000
Trading securities	255,027,000
Successor | Measured at fair value on a recurring basis | Level 2 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities, fair value	1,811,470,000
Trading securities	149,683,000
Successor | Measured at fair value on a recurring basis | Level 2 | Other asset-backed securities
Assets:
Available-for-sale securities, fair value	648,929,000
Trading securities	115,521,000
Successor | Measured at fair value on a recurring basis | Level 2 | U.S. government-related securities
Assets:
Available-for-sale securities, fair value	266,139,000
Trading securities	4,537,000
Successor | Measured at fair value on a recurring basis | Level 2 | States, municipals, and political subdivisions
Assets:
Available-for-sale securities, fair value	1,656,503,000
Trading securities	316,519,000
Successor | Measured at fair value on a recurring basis | Level 2 | Other government-related securities
Assets:
Available-for-sale securities, fair value	239,921,000
Trading securities	63,012,000
Successor | Measured at fair value on a recurring basis | Level 2 | Corporate securities
Assets:
Available-for-sale securities, fair value	26,707,519,000
Trading securities	1,619,097,000
Successor | Measured at fair value on a recurring basis | Level 2 | Preferred stock
Assets:
Available-for-sale securities, fair value	19,062,000
Successor | Measured at fair value on a recurring basis | Level 3
Assets:
Total fixed maturity securities	1,316,708,000
Equity securities	69,010,000
Other long-term investments	124,325,000
Total investments	1,510,043,000
Assets related to separate accounts
Total assets measured at fair value on a recurring basis	1,510,043,000
Liabilities:
Annuity account balances	87,616,000
Other liabilities	571,843,000
Total liabilities measured at fair value on a recurring basis	659,459,000
Successor | Measured at fair value on a recurring basis | Level 3 | Fixed maturities
Assets:
Available-for-sale securities, fair value	1,226,653,000
Trading securities	90,055,000
Successor | Measured at fair value on a recurring basis | Level 3 | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value	3,000
Successor | Measured at fair value on a recurring basis | Level 3 | Other asset-backed securities
Assets:
Available-for-sale securities, fair value	562,604,000
Trading securities	84,563,000
Successor | Measured at fair value on a recurring basis | Level 3 | Corporate securities
Assets:
Available-for-sale securities, fair value	664,046,000
Trading securities	5,492,000
Successor | Measured at fair value on a recurring basis | Fair Values
Assets:
Total fixed maturity securities	38,183,337,000
Equity securities	754,489,000
Other long-term investments	542,243,000
Short-term investments	332,431,000
Total investments	39,812,500,000
Cash	348,182,000
Other assets	23,830,000
Assets related to separate accounts
Variable annuity	13,244,252,000
Variable universal life	895,925,000
Total assets measured at fair value on a recurring basis	54,324,689,000
Liabilities:
Annuity account balances	87,616,000
Other liabilities	748,821,000
Total liabilities measured at fair value on a recurring basis	836,437,000
Successor | Measured at fair value on a recurring basis | Fair Values | Fixed maturities
Assets:
Available-for-sale securities, fair value	35,543,477,000
Trading securities	2,639,860,000
Successor | Measured at fair value on a recurring basis | Fair Values | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value	1,898,483,000
Trading securities	255,027,000
Successor | Measured at fair value on a recurring basis | Fair Values | Commercial mortgage-backed securities
Assets:
Available-for-sale securities, fair value	1,811,470,000
Trading securities	149,683,000
Successor | Measured at fair value on a recurring basis | Fair Values | Other asset-backed securities
Assets:
Available-for-sale securities, fair value	1,211,533,000
Trading securities	200,084,000
Successor | Measured at fair value on a recurring basis | Fair Values | U.S. government-related securities
Assets:
Available-for-sale securities, fair value	1,268,159,000
Trading securities	26,961,000
Successor | Measured at fair value on a recurring basis | Fair Values | States, municipals, and political subdivisions
Assets:
Available-for-sale securities, fair value	1,656,503,000
Trading securities	316,519,000
Successor | Measured at fair value on a recurring basis | Fair Values | Other government-related securities
Assets:
Available-for-sale securities, fair value	239,921,000
Trading securities	63,012,000
Successor | Measured at fair value on a recurring basis | Fair Values | Corporate securities
Assets:
Available-for-sale securities, fair value	27,371,565,000
Trading securities	1,624,589,000
Successor | Measured at fair value on a recurring basis | Fair Values | Preferred stock
Assets:
Available-for-sale securities, fair value	85,843,000
Trading securities	$ 3,985,000
Predecessor
Liabilities:
Transfers from Level 1 to Level 2		21,000,000	$ 0
Predecessor | Level 3 | Other asset-backed securities
Assets:
Total investments		587,031,000
Predecessor | Level 3 | Corporate securities
Assets:
Total investments		875,810,000
Predecessor | Measured at fair value on a recurring basis | Level 1
Assets:
Total fixed maturity securities		1,333,895,000
Equity securities		656,437,000
Other long-term investments		113,699,000
Short-term investments		261,947,000
Total investments		2,365,978,000
Cash		396,072,000
Other assets		19,099,000
Assets related to separate accounts
Variable annuity		12,829,188,000
Variable universal life		827,610,000
Total assets measured at fair value on a recurring basis		16,437,947,000
Liabilities:
Other liabilities		40,067,000
Total liabilities measured at fair value on a recurring basis		40,067,000
Predecessor | Measured at fair value on a recurring basis | Level 1 | Fixed maturities
Assets:
Available-for-sale securities, fair value		1,097,509,000
Trading securities		236,386,000
Predecessor | Measured at fair value on a recurring basis | Level 1 | U.S. government-related securities
Assets:
Available-for-sale securities, fair value		1,054,353,000
Trading securities		233,592,000
Predecessor | Measured at fair value on a recurring basis | Level 1 | Corporate securities
Assets:
Available-for-sale securities, fair value		83,000
Predecessor | Measured at fair value on a recurring basis | Level 1 | Preferred stock
Assets:
Available-for-sale securities, fair value		43,073,000
Trading securities		2,794,000
Predecessor | Measured at fair value on a recurring basis | Level 2
Assets:
Total fixed maturity securities		32,579,065,000
Equity securities		13,063,000
Other long-term investments		141,487,000
Short-term investments		6,771,000
Total investments		32,740,386,000
Assets related to separate accounts
Total assets measured at fair value on a recurring basis		32,740,386,000
Liabilities:
Other liabilities		3,932,000
Total liabilities measured at fair value on a recurring basis		3,932,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | Fixed maturities
Assets:
Available-for-sale securities, fair value		30,322,539,000
Trading securities		2,256,526,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value		1,765,270,000
Trading securities		286,658,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities, fair value		1,286,887,000
Trading securities		146,743,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | Other asset-backed securities
Assets:
Available-for-sale securities, fair value		210,020,000
Trading securities		122,511,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | U.S. government-related securities
Assets:
Available-for-sale securities, fair value		477,824,000
Trading securities		4,755,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | States, municipals, and political subdivisions
Assets:
Available-for-sale securities, fair value		1,603,600,000
Trading securities		313,354,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | Other government-related securities
Assets:
Available-for-sale securities, fair value		17,740,000
Trading securities		58,827,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | Corporate securities
Assets:
Available-for-sale securities, fair value		24,941,584,000
Trading securities		1,322,276,000
Predecessor | Measured at fair value on a recurring basis | Level 2 | Preferred stock
Assets:
Available-for-sale securities, fair value		19,614,000
Trading securities		1,402,000
Predecessor | Measured at fair value on a recurring basis | Level 3
Assets:
Total fixed maturity securities		1,660,290,000
Equity securities		69,763,000
Other long-term investments		96,830,000
Total investments		1,826,883,000
Assets related to separate accounts
Total assets measured at fair value on a recurring basis		1,826,883,000
Liabilities:
Annuity account balances		92,512,000
Other liabilities		585,556,000
Total liabilities measured at fair value on a recurring basis		678,068,000
Predecessor | Measured at fair value on a recurring basis | Level 3 | Fixed maturities
Assets:
Available-for-sale securities, fair value		1,489,153,000
Trading securities		171,137,000
Predecessor | Measured at fair value on a recurring basis | Level 3 | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value		3,000
Predecessor | Measured at fair value on a recurring basis | Level 3 | Other asset-backed securities
Assets:
Available-for-sale securities, fair value		587,031,000
Trading securities		152,912,000
Predecessor | Measured at fair value on a recurring basis | Level 3 | Corporate securities
Assets:
Available-for-sale securities, fair value		902,119,000
Trading securities		18,225,000
Predecessor | Measured at fair value on a recurring basis | Fair Values
Assets:
Total fixed maturity securities		35,573,250,000
Equity securities		739,263,000
Other long-term investments		352,016,000
Short-term investments		268,718,000
Total investments		36,933,247,000
Cash		396,072,000
Other assets		19,099,000
Assets related to separate accounts
Variable annuity		12,829,188,000
Variable universal life		827,610,000
Total assets measured at fair value on a recurring basis		51,005,216,000
Liabilities:
Annuity account balances		92,512,000
Other liabilities		629,555,000
Total liabilities measured at fair value on a recurring basis		722,067,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | Fixed maturities
Assets:
Available-for-sale securities, fair value		32,909,201,000
Trading securities		2,664,049,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value		1,765,273,000
Trading securities		286,658,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | Commercial mortgage-backed securities
Assets:
Available-for-sale securities, fair value		1,286,887,000
Trading securities		146,743,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | Other asset-backed securities
Assets:
Available-for-sale securities, fair value		797,051,000
Trading securities		275,423,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | U.S. government-related securities
Assets:
Available-for-sale securities, fair value		1,532,177,000
Trading securities		238,347,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | States, municipals, and political subdivisions
Assets:
Available-for-sale securities, fair value		1,603,600,000
Trading securities		313,354,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | Other government-related securities
Assets:
Available-for-sale securities, fair value		17,740,000
Trading securities		58,827,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | Corporate securities
Assets:
Available-for-sale securities, fair value		25,843,786,000
Trading securities		1,340,501,000
Predecessor | Measured at fair value on a recurring basis | Fair Values | Preferred stock
Assets:
Available-for-sale securities, fair value		62,687,000
Trading securities		$ 4,196,000