Employee Benefit Plans (Schedule of Defined Benefit Plans Disclosures) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Curtailments		$ 3,600
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year		212,392	$ 212,392
Value of Plan Assets at end of year	$ 274,225			$ 212,392
Pension Benefits [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at end of year	252,278
Predecessor [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost			3,465	4,282	$ 1,734
Interest cost			3,184	3,944	2,914
Predecessor [Member] | Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	341,427	301,292	301,292	353,736
Service cost	0		0	9	21,478
Interest cost			9,338	14,604	17,070
Re-entry of former Magnum employees			0	0
Settlements			0	0
Curtailments			454
Benefits paid			(8,699)	(61,955)
Other-primarily actuarial gain			0	(5,102)
Benefit Obligations at end of year			341,427	301,292	353,736
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	292,726	273,499	273,499	336,709
Actual return on plan assets			27,811	(1,679)
Employer contributions			115	424
Benefits paid			(8,699)	(61,955)
Value of Plan Assets at end of year			292,726	273,499	336,709
Accrued benefit cost			(48,701)	(27,793)
Prior service credit (cost)			0	0
Accumulated gain (loss)			0	(16,769)
Total not yet recognized as a component of net periodic benefit cost			0	(16,769)
Current liability			(420)	(420)
Noncurrent liability			(48,281)	(27,373)
Pension and Other Postretirement Defined Benefit Plans, Liabilities			(48,701)	(27,793)
Fresh start accounting adjustment			39,042	0
Predecessor [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	120,311	103,460	103,460	36,098
Service cost			393	866	1,649
Interest cost			3,223	1,904	1,841
Re-entry of former Magnum employees			0	85,843
Settlements			0	0
Curtailments			714	0
Benefits paid			(8,273)	(3,646)
Other-primarily actuarial gain			0	(17,605)
Benefit Obligations at end of year			120,311	103,460	36,098
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	0	$ 0	0	0
Actual return on plan assets			0	0
Employer contributions			8,273	3,646
Benefits paid			(8,273)	(3,646)
Value of Plan Assets at end of year			0	0	$ 0
Accrued benefit cost			(120,311)	(103,460)
Prior service credit (cost)			0	26,944
Accumulated gain (loss)			0	11,313
Total not yet recognized as a component of net periodic benefit cost			0	38,257
Current liability			(8,352)	(3,650)
Noncurrent liability			(111,959)	(99,810)
Pension and Other Postretirement Defined Benefit Plans, Liabilities			(120,311)	$ (103,460)
Fresh start accounting adjustment			20,794
Successor [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	1,583
Interest cost	1,126
Successor [Member] | Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	341,427
Service cost	0
Interest cost	2,768
Re-entry of former Magnum employees	0
Settlements	(135)
Curtailments	0
Benefits paid	(11,009)
Other-primarily actuarial gain	(19,422)
Benefit Obligations at end of year	313,629		341,427
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	292,726
Actual return on plan assets	(7,899)
Employer contributions	407
Benefits paid	(11,009)
Value of Plan Assets at end of year	274,225		292,726
Accrued benefit cost	(39,404)
Prior service credit (cost)	0
Accumulated gain (loss)	6,751
Total not yet recognized as a component of net periodic benefit cost	6,751
Current liability	(520)
Noncurrent liability	(38,884)
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(39,404)
Fresh start accounting adjustment	0
Successor [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	120,311
Service cost	180
Interest cost	978
Re-entry of former Magnum employees	0
Settlements	0
Curtailments	0
Benefits paid	(1,962)
Other-primarily actuarial gain	(7,640)
Benefit Obligations at end of year	111,867		120,311
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	0
Employer contributions	1,962
Benefits paid	(1,962)
Value of Plan Assets at end of year	0		$ 0
Accrued benefit cost	(111,867)
Prior service credit (cost)	0
Accumulated gain (loss)	7,640
Total not yet recognized as a component of net periodic benefit cost	7,640
Current liability	(10,422)
Noncurrent liability	(101,445)
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(111,867)
Fresh start accounting adjustment	$ 0