EMPLOYEE BENEFIT PLANS - Defined Benefit Pension Plan and Unfunded Excess Benefit Plan (Details) - USD ($) $ in Thousands	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Successor | Defined Benefit Pension Plan
EMPLOYEE BENEFIT PLANS
Accumulated benefit obligation, end of year		$ 250,133	$ 250,133
Change in projected benefit obligation:
Projected benefit obligation at beginning of year		281,099
Service cost		11,220
Interest cost		9,072
Amendments		0
Actuarial loss/(gain)		(19,235)
Benefits paid		(13,935)
Projected benefit obligation at end of year	$ 281,099	268,221	268,221
Change in plan assets:
Fair value of plan assets at beginning of year		201,820
Actual return on plan assets		6,751
Employer contributions		1,406
Benefits paid		(13,935)
Fair value of plan assets at end of year	201,820	196,042	196,042
After reflecting FASB guidance:
Funded status		(72,179)	(72,179)
Amounts recognized in the balance sheet:
Other liabilities		(72,179)	(72,179)
Amounts recognized in accumulated other comprehensive income:
Net actuarial loss/(gain)		(12,772)	(12,772)
Prior service cost/(credit)		0	0
Total amounts recognized in AOCI		(12,772)	(12,772)
Successor | Unfunded Excess Benefit Plan
EMPLOYEE BENEFIT PLANS
Accumulated benefit obligation, end of year		54,196	54,196
Change in projected benefit obligation:
Projected benefit obligation at beginning of year		51,243
Service cost		1,229
Interest cost		1,499
Amendments		0
Actuarial loss/(gain)		4,484
Benefits paid		(1,470)
Projected benefit obligation at end of year	51,243	56,985	56,985
Change in plan assets:
Fair value of plan assets at beginning of year		0
Actual return on plan assets		0
Employer contributions		1,470
Benefits paid		(1,470)
Fair value of plan assets at end of year	0	0	0
After reflecting FASB guidance:
Funded status		(56,985)	(56,985)
Amounts recognized in the balance sheet:
Other liabilities		(56,985)	(56,985)
Amounts recognized in accumulated other comprehensive income:
Net actuarial loss/(gain)		4,484	4,484
Prior service cost/(credit)		0	0
Total amounts recognized in AOCI		4,484	4,484
Successor | Retiree medical plan
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	247		247
Service cost			1
Interest cost			2
Actuarial loss/(gain)			(113)
Plan participant contributions			141
Benefits paid			(141)
Projected benefit obligation at end of year		137	137	$ 247
Change in plan assets:
Benefits paid			(141)
Successor | Group life insurance plan
Change in projected benefit obligation:
Projected benefit obligation at beginning of year		9,781
Service cost		138
Interest cost		336
Actuarial loss/(gain)		(894)
Benefits paid		(298)
Projected benefit obligation at end of year	9,781	9,063	9,063
Change in plan assets:
Benefits paid		(298)
Predecessor | Defined Benefit Pension Plan
EMPLOYEE BENEFIT PLANS
Accumulated benefit obligation, end of year	262,290			249,453
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	267,331	281,099	267,331	219,152
Service cost	974			9,411	$ 9,345
Interest cost	1,002			10,493	8,985
Amendments	0			0
Actuarial loss/(gain)	12,384			38,110
Benefits paid	(592)			(9,835)
Projected benefit obligation at end of year	281,099			267,331	219,152
Change in plan assets:
Fair value of plan assets at beginning of year	203,772	201,820	203,772	180,173
Actual return on plan assets	(3,525)			17,921
Employer contributions	2,165			15,513
Benefits paid	(592)			(9,835)
Fair value of plan assets at end of year	201,820			203,772	180,173
After reflecting FASB guidance:
Funded status	(79,279)			(63,559)
Amounts recognized in the balance sheet:
Other liabilities	(79,279)			(63,559)
Amounts recognized in accumulated other comprehensive income:
Net actuarial loss/(gain)	96,965			80,430
Prior service cost/(credit)	(1,001)			(1,033)
Total amounts recognized in AOCI	95,964			79,397
Predecessor | Unfunded Excess Benefit Plan
EMPLOYEE BENEFIT PLANS
Accumulated benefit obligation, end of year	49,251			47,368
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	49,575	51,243	49,575	39,679
Service cost	95			954	1,037
Interest cost	140			1,696	1,387
Amendments	0			0
Actuarial loss/(gain)	1,555			9,153
Benefits paid	(122)			(1,907)
Projected benefit obligation at end of year	51,243			49,575	39,679
Change in plan assets:
Fair value of plan assets at beginning of year	0	0	0	0
Actual return on plan assets	0			0
Employer contributions	122			1,907
Benefits paid	(122)			(1,907)
Fair value of plan assets at end of year	0			0	0
After reflecting FASB guidance:
Funded status	(51,243)			(49,575)
Amounts recognized in the balance sheet:
Other liabilities	(51,243)			(49,575)
Amounts recognized in accumulated other comprehensive income:
Net actuarial loss/(gain)	22,401			20,983
Prior service cost/(credit)	23			24
Total amounts recognized in AOCI	22,424			21,007
Predecessor | Retiree medical plan
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	247		247	447
Service cost				2
Interest cost				4
Actuarial loss/(gain)				30
Plan participant contributions				254
Benefits paid				(490)
Projected benefit obligation at end of year				247	447
Change in plan assets:
Benefits paid				(490)
Predecessor | Group life insurance plan
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	9,288	$ 9,781	$ 9,288	8,653
Service cost	12			97
Interest cost	39			416
Actuarial loss/(gain)	511			694
Benefits paid	(69)			(572)
Projected benefit obligation at end of year	9,781			9,288	$ 8,653
Change in plan assets:
Benefits paid	$ (69)			$ (572)