INCOME TAXES - Effective Income Tax Rate and Components of Income Tax and Deferred Liability (Details) - USD ($) $ in Thousands	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2014
Successor
Effective income tax rate related to continuing operations
Statutory federal income tax rate applied to pre-tax income (as a percent)		35.00%	35.00%
State income taxes (as a percent)		1.40%	0.60%
Investment income not subject to tax (as a percent)		(6.80%)	(3.10%)
Uncertain tax positions (as a percent)		0.00%	0.30%
Other (as a percent)		(0.30%)	(0.30%)
Effective income tax rate (as a percent)		29.30%	32.50%
Current income tax expense:
Federal		$ 50,722	$ (41,244)
State		(4,000)	2,581
Total current		46,722	(38,663)
Deferred income tax expense:
Federal		18,880	204,810
State		8,889	3,926
Total deferred		27,769	208,736
Deferred income tax assets:
Loss and credit carryforwards		115,667	510,886
Deferred compensation		108,416	101,626
Deferred policy acquisition costs		267,542	155,009
Premium on non-recourse funding obligations		13,872	4,482
Net unrealized loss on investments		671,176	353,149
Other		6,605	0
Valuation allowance		(3,466)	(5,039)
Deferred income tax assets		1,179,812	1,120,113
Deferred income tax liabilities:
Premium receivables and policy liabilities		202,753	819,476
VOBA and other intangibles		632,176	720,878
Invested assets (other than unrealized gains (losses))		1,560,063	1,340,688
Other		0	30,032
Deferred income tax liabilities		2,394,992	2,911,074
Net deferred income tax liability		(1,215,180)	(1,790,961)
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance, beginning of period		105,850	8,937
Additions for tax positions of the current year		2,213	2,122
Additions for tax positions of prior years		1,812	1,318
Reductions of tax positions of prior years:
Changes in judgment		(644)	(975)
Settlements during the period		(100,294)	(1,546)
Lapses of applicable statute of limitations		0	0
Balance, end of period	$ 105,850	8,937	$ 9,856
Predecessor
Effective income tax rate related to continuing operations
Statutory federal income tax rate applied to pre-tax income (as a percent)	35.00%			35.00%
State income taxes (as a percent)	0.50%			0.50%
Investment income not subject to tax (as a percent)	(2.80%)			(2.70%)
Uncertain tax positions (as a percent)	0.00%			0.50%
Other (as a percent)	0.70%			0.10%
Effective income tax rate (as a percent)	33.40%			33.40%
Current income tax expense:
Federal	$ (48,469)			$ 176,238
State	1,085			5,525
Total current	(47,384)			181,763
Deferred income tax expense:
Federal	90,774			65,566
State	935			(491)
Total deferred	91,709			65,075
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance, beginning of period	168,076	$ 105,850		85,846
Additions for tax positions of the current year	(5,010)			57,392
Additions for tax positions of prior years	1,149			34,371
Reductions of tax positions of prior years:
Changes in judgment	(58,365)			(9,533)
Settlements during the period	0			0
Lapses of applicable statute of limitations	0			0
Balance, end of period	$ 105,850			$ 168,076