INVESTMENT OPERATIONS - Schedule of Gross Unrealized Losses and Fair Value of Investments Not Deemed to be Other-Than-Temporary (Details) - Successor - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value
Less Than 12 Months	$ 18,169,517	$ 30,237,469
12 Months or More	10,955,615	0
Total	29,125,132	30,237,469
Unrealized Loss
Less Than 12 Months	(663,606)	(2,929,180)
12 Months or More	(1,196,101)	0
Total	(1,859,707)	(2,929,180)
Residential mortgage-backed securities
Fair Value
Less Than 12 Months	1,051,694	977,433
12 Months or More	170,826	0
Total	1,222,520	977,433
Unrealized Loss
Less Than 12 Months	(21,178)	(17,112)
12 Months or More	(4,117)	0
Total	(25,295)	(17,112)
Commercial mortgage-backed securities
Fair Value
Less Than 12 Months	1,426,252	1,232,495
12 Months or More	100,475	0
Total	1,526,727	1,232,495
Unrealized Loss
Less Than 12 Months	(36,589)	(41,852)
12 Months or More	(4,013)	0
Total	(40,602)	(41,852)
Other asset-backed securities
Fair Value
Less Than 12 Months	323,706	633,274
12 Months or More	176,792	0
Total	500,498	633,274
Unrealized Loss
Less Than 12 Months	(9,291)	(18,763)
12 Months or More	(11,407)	0
Total	(20,698)	(18,763)
U.S. government-related securities
Fair Value
Less Than 12 Months	1,237,942	1,291,476
12 Months or More	3	0
Total	1,237,945	1,291,476
Unrealized Loss
Less Than 12 Months	(40,454)	(34,532)
12 Months or More	(1)	0
Total	(40,455)	(34,532)
Other government-related securities
Fair Value
Less Than 12 Months	98,412	17,740
12 Months or More	79,393	0
Total	177,805	17,740
Unrealized Loss
Less Than 12 Months	(2,907)	(743)
12 Months or More	(11,890)	0
Total	(14,797)	(743)
States, municipals, and political subdivisions
Fair Value
Less Than 12 Months	1,062,368	1,566,752
12 Months or More	548,254	0
Total	1,610,622	1,566,752
Unrealized Loss
Less Than 12 Months	(63,809)	(126,814)
12 Months or More	(41,749)
Total	(105,558)	(126,814)
Corporate securities
Fair Value
Less Than 12 Months	12,490,517	24,235,121
12 Months or More	9,791,313
Total	22,281,830	24,235,121
Unrealized Loss
Less Than 12 Months	(467,463)	(2,681,020)
12 Months or More	(1,114,635)	0
Total	(1,582,098)	(2,681,020)
Preferred Stock
Fair Value
Less Than 12 Months	66,781	34,685
12 Months or More	19,062	0
Total	85,843	34,685
Unrealized Loss
Less Than 12 Months	(6,642)	(1,867)
12 Months or More	(1,877)	0
Total	(8,519)	(1,867)
Equity securities
Fair Value
Less Than 12 Months	411,845	248,493
12 Months or More	69,497	0
Total	481,342	248,493
Unrealized Loss
Less Than 12 Months	(15,273)	(6,477)
12 Months or More	(6,412)	0
Total	$ (21,685)	$ (6,477)