INVESTMENT OPERATIONS - Schedule of Amortized Cost and Fair Value of the Company's Investments Classified as Available-for-Sale (Details) - Successor - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Investment [Line Items]
Amortized Cost	$ 37,429,686	$ 36,724,217
Gross Unrealized Gains	207,104	53,419
Gross Unrealized Losses	(2,110,871)	(2,930,440)
Available-for-sale securities, fair value	35,525,919	33,847,196
Total OTTI Recognized in OCI	152	(605)
Residential mortgage-backed securities
Investment [Line Items]
Amortized Cost	1,849,678	1,773,099
Gross Unrealized Gains	31,231	9,286
Gross Unrealized Losses	(10,032)	(17,112)
Available-for-sale securities, fair value	1,870,877	1,765,273
Total OTTI Recognized in OCI	0	0
Commercial mortgage-backed securities
Investment [Line Items]
Amortized Cost	1,465,623	1,328,317
Gross Unrealized Gains	9,163	428
Gross Unrealized Losses	(12,089)	(41,858)
Available-for-sale securities, fair value	1,462,697	1,286,887
Total OTTI Recognized in OCI	0	0
Other asset-backed securities
Investment [Line Items]
Amortized Cost	992,128	813,056
Gross Unrealized Gains	813	2,758
Gross Unrealized Losses	(29,403)	(18,763)
Available-for-sale securities, fair value	963,538	797,051
Total OTTI Recognized in OCI	0	0
U.S. government-related securities
Investment [Line Items]
Amortized Cost	1,433,945	1,566,260
Gross Unrealized Gains	7,171	449
Gross Unrealized Losses	(2,236)	(34,532)
Available-for-sale securities, fair value	1,438,880	1,532,177
Total OTTI Recognized in OCI	0	0
Other government-related securities
Investment [Line Items]
Amortized Cost	18,667	18,483
Gross Unrealized Gains	40	0
Gross Unrealized Losses	(71)	(743)
Available-for-sale securities, fair value	18,636	17,740
Total OTTI Recognized in OCI	0	0
States, municipals, and political subdivisions
Investment [Line Items]
Amortized Cost	1,729,964	1,729,732
Gross Unrealized Gains	2,865	682
Gross Unrealized Losses	(71,269)	(126,814)
Available-for-sale securities, fair value	1,661,560	1,603,600
Total OTTI Recognized in OCI	0	0
Corporate securities
Investment [Line Items]
Amortized Cost	28,760,422	28,499,691
Gross Unrealized Gains	141,011	26,369
Gross Unrealized Losses	(1,976,233)	(2,682,274)
Available-for-sale securities, fair value	26,925,200	25,843,786
Total OTTI Recognized in OCI	152	(605)
Preferred stock
Investment [Line Items]
Amortized Cost	64,362	64,362
Gross Unrealized Gains	396	192
Gross Unrealized Losses	(1,795)	(1,867)
Available-for-sale securities, fair value	62,963	62,687
Total OTTI Recognized in OCI	0	0
Fixed maturities
Investment [Line Items]
Amortized Cost	36,314,789	35,793,000
Gross Unrealized Gains	192,690	40,164
Gross Unrealized Losses	(2,103,128)	(2,923,963)
Available-for-sale securities, fair value	34,404,351	32,909,201
Total OTTI Recognized in OCI	152	(605)
Equity securities
Investment [Line Items]
Amortized Cost	708,667	724,226
Gross Unrealized Gains	14,414	13,255
Gross Unrealized Losses	(7,743)	(6,477)
Available-for-sale securities, fair value	715,338	731,004
Total OTTI Recognized in OCI	0	0
Short-term investments
Investment [Line Items]
Amortized Cost	406,230	206,991
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale securities, fair value	406,230	206,991
Total OTTI Recognized in OCI	$ 0	$ 0

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount before tax of other than temporary impairment (OTTI) on investment in available-for-sale debt security, recognized in other comprehensive loss.

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