INVESTMENT OPERATIONS - Schedule of Investments' Gross Unrealized Losses and Fair Value of the Company's Investments that are Not Deemed to be Other-than-Temporarily Impaired (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Successor
Fair Value
Less Than 12 Months	$ 18,267,283
12 Months or More	10,957,881
Total	29,225,164
Unrealized Loss
Less Than 12 Months	(666,780)
12 Months or More	(1,196,195)
Total	(1,862,975)
Successor | Residential mortgage-backed securities
Fair Value
Less Than 12 Months	1,060,569
12 Months or More	170,826
Total	1,231,395
Unrealized Loss
Less Than 12 Months	(21,550)
12 Months or More	(4,117)
Total	(25,667)
Successor | Commercial mortgage-backed securities
Fair Value
Less Than 12 Months	1,452,146
12 Months or More	100,475
Total	1,552,621
Unrealized Loss
Less Than 12 Months	(37,665)
12 Months or More	(4,013)
Total	(41,678)
Successor | Other asset-backed securities
Fair Value
Less Than 12 Months	323,706
12 Months or More	176,792
Total	500,498
Unrealized Loss
Less Than 12 Months	(9,291)
12 Months or More	(11,407)
Total	(20,698)
Successor | U.S. government-related securities
Fair Value
Less Than 12 Months	1,237,942
12 Months or More	3
Total	1,237,945
Unrealized Loss
Less Than 12 Months	(40,454)
12 Months or More	(1)
Total	(40,455)
Successor | Other government-related securities
Fair Value
Less Than 12 Months	98,412
12 Months or More	79,393
Total	177,805
Unrealized Loss
Less Than 12 Months	(2,907)
12 Months or More	(11,890)
Total	(14,797)
Successor | States, municipals, and political subdivisions
Fair Value
Less Than 12 Months	1,062,368
12 Months or More	548,254
Total	1,610,622
Unrealized Loss
Less Than 12 Months	(63,809)
12 Months or More	(41,749)
Total	(105,558)
Successor | Corporate securities
Fair Value
Less Than 12 Months	12,553,514
12 Months or More	9,793,579
Total	22,347,093
Unrealized Loss
Less Than 12 Months	(469,189)
12 Months or More	(1,114,729)
Total	(1,583,918)
Successor | Preferred stock
Fair Value
Less Than 12 Months	66,781
12 Months or More	19,062
Total	85,843
Unrealized Loss
Less Than 12 Months	(6,642)
12 Months or More	(1,877)
Total	(8,519)
Successor | Equity securities
Fair Value
Less Than 12 Months	411,845
12 Months or More	69,497
Total	481,342
Unrealized Loss
Less Than 12 Months	(15,273)
12 Months or More	(6,412)
Total	$ (21,685)
Predecessor
Fair Value
Less Than 12 Months		$ 30,286,819
12 Months or More		0
Total		30,286,819
Unrealized Loss
Less Than 12 Months		(2,930,440)
12 Months or More		0
Total		(2,930,440)
Predecessor | Residential mortgage-backed securities
Fair Value
Less Than 12 Months		977,433
12 Months or More		0
Total		977,433
Unrealized Loss
Less Than 12 Months		(17,112)
12 Months or More		0
Total		(17,112)
Predecessor | Commercial mortgage-backed securities
Fair Value
Less Than 12 Months		1,233,518
12 Months or More		0
Total		1,233,518
Unrealized Loss
Less Than 12 Months		(41,858)
12 Months or More		0
Total		(41,858)
Predecessor | Other asset-backed securities
Fair Value
Less Than 12 Months		633,274
12 Months or More		0
Total		633,274
Unrealized Loss
Less Than 12 Months		(18,763)
12 Months or More		0
Total		(18,763)
Predecessor | U.S. government-related securities
Fair Value
Less Than 12 Months		1,291,476
12 Months or More		0
Total		1,291,476
Unrealized Loss
Less Than 12 Months		(34,532)
12 Months or More		0
Total		(34,532)
Predecessor | Other government-related securities
Fair Value
Less Than 12 Months		17,740
12 Months or More		0
Total		17,740
Unrealized Loss
Less Than 12 Months		(743)
12 Months or More		0
Total		(743)
Predecessor | States, municipals, and political subdivisions
Fair Value
Less Than 12 Months		1,566,752
12 Months or More		0
Total		1,566,752
Unrealized Loss
Less Than 12 Months		(126,814)
12 Months or More		0
Total		(126,814)
Predecessor | Corporate securities
Fair Value
Less Than 12 Months		24,283,448
12 Months or More		0
Total		24,283,448
Unrealized Loss
Less Than 12 Months		(2,682,274)
12 Months or More		0
Total		(2,682,274)
Predecessor | Preferred stock
Fair Value
Less Than 12 Months		34,685
12 Months or More		0
Total		34,685
Unrealized Loss
Less Than 12 Months		(1,867)
12 Months or More		0
Total		(1,867)
Predecessor | Equity securities
Fair Value
Less Than 12 Months		248,493
12 Months or More		0
Total		248,493
Unrealized Loss
Less Than 12 Months		(6,477)
12 Months or More		0
Total		$ (6,477)