INVESTMENT OPERATIONS - Schedule of Amortized Cost and Fair Value of the Company's Investments Classified as Available-for-Sale (Details) - Successor - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2016	Dec. 31, 2015
Investment [Line Items]
Amortized Cost	$ 37,625,082	$ 36,724,217
Gross Unrealized Gains	546,687	53,419
Gross Unrealized Losses	(1,129,679)	(2,930,440)
Available-for-sale securities, fair value	37,042,090	33,847,196
Total OTTI Recognized in OCI	(4,561)	(605)
Residential mortgage-backed securities
Investment [Line Items]
Amortized Cost	1,900,934	1,773,099
Gross Unrealized Gains	50,003	9,286
Gross Unrealized Losses	(9,253)	(17,112)
Available-for-sale securities, fair value	1,941,684	1,765,273
Total OTTI Recognized in OCI	(1)	0
Commercial mortgage-backed securities
Investment [Line Items]
Amortized Cost	1,570,208	1,328,317
Gross Unrealized Gains	30,278	428
Gross Unrealized Losses	(3,726)	(41,858)
Available-for-sale securities, fair value	1,596,760	1,286,887
Total OTTI Recognized in OCI	0	0
Other asset-backed securities
Investment [Line Items]
Amortized Cost	1,151,430	813,056
Gross Unrealized Gains	5,267	2,758
Gross Unrealized Losses	(36,055)	(18,763)
Available-for-sale securities, fair value	1,120,642	797,051
Total OTTI Recognized in OCI	0	0
U.S. government-related securities
Investment [Line Items]
Amortized Cost	1,350,769	1,566,260
Gross Unrealized Gains	21,232	449
Gross Unrealized Losses	(205)	(34,532)
Available-for-sale securities, fair value	1,371,796	1,532,177
Total OTTI Recognized in OCI	0	0
Other government-related securities
Investment [Line Items]
Amortized Cost	18,348	18,483
Gross Unrealized Gains	332	0
Gross Unrealized Losses	0	(743)
Available-for-sale securities, fair value	18,680	17,740
Total OTTI Recognized in OCI	0	0
States, municipals, and political subdivisions
Investment [Line Items]
Amortized Cost	1,727,664	1,729,732
Gross Unrealized Gains	31,429	682
Gross Unrealized Losses	(21,594)	(126,814)
Available-for-sale securities, fair value	1,737,499	1,603,600
Total OTTI Recognized in OCI	0	0
Corporate securities
Investment [Line Items]
Amortized Cost	28,883,011	28,499,691
Gross Unrealized Gains	380,022	26,369
Gross Unrealized Losses	(1,052,087)	(2,682,274)
Available-for-sale securities, fair value	28,210,946	25,843,786
Total OTTI Recognized in OCI	(4,560)	(605)
Preferred stock
Investment [Line Items]
Amortized Cost	64,362	64,362
Gross Unrealized Gains	1,732	192
Gross Unrealized Losses	(1,667)	(1,867)
Available-for-sale securities, fair value	64,427	62,687
Total OTTI Recognized in OCI	0	0
Fixed maturities
Investment [Line Items]
Amortized Cost	36,666,726	35,793,000
Gross Unrealized Gains	520,295	40,164
Gross Unrealized Losses	(1,124,587)	(2,923,963)
Available-for-sale securities, fair value	36,062,434	32,909,201
Total OTTI Recognized in OCI	(4,561)	(605)
Equity securities
Investment [Line Items]
Amortized Cost	710,361	724,226
Gross Unrealized Gains	26,392	13,255
Gross Unrealized Losses	(5,092)	(6,477)
Available-for-sale securities, fair value	731,661	731,004
Total OTTI Recognized in OCI	0	0
Short-term investments
Investment [Line Items]
Amortized Cost	247,995	206,991
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale securities, fair value	247,995	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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