CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Paid-in Capital	Retained Earnings (Accumulated Deficit)	Deferred Compensation Obligation	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax | Predecessor [Member]	$ (173)						$ (173)
Balance as of beginning of period (in shares) (Predecessor [Member]) at Dec. 31, 2014			71,569,000
Balance as of beginning of period (Predecessor [Member]) at Dec. 31, 2014	675,817	$ 4,044	$ 529	$ 1,206,305	$ (535,176)	$ 3,211	249	$ (3,345)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) | Predecessor [Member]	(1,582,961)				(1,582,961)
Dividends declared on preferred stock | Predecessor [Member]	(12,134)				(12,134)			0
Conversion of preferred stock (in shares) | Predecessor [Member]			9,414,000
Conversion of preferred stock | Predecessor [Member]	0	(898)	$ (94)	(804)	0
Share-based compensation (in shares) | Predecessor [Member]			195,000
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition | Predecessor [Member]	4,540		$ 4	4,536
Deferred compensation (in shares) | Predecessor [Member]			2,000
Deferred Compensation Obligation | Predecessor [Member]	0			0		229		(229)
Restricted stock unit vesting (in shares) | Predecessor [Member]			73,000
Other | Predecessor [Member]				0
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures | Predecessor [Member]	(556)		$ 1	(557)
Balance as of end of period (in shares) (Predecessor [Member]) at Dec. 31, 2015			81,253,000
Balance as of end of period (Predecessor [Member]) at Dec. 31, 2015	(915,121)	3,146	$ 628	1,211,088	(2,130,271)	3,440	422	(3,574)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax | Predecessor [Member]	421
Net income (loss) | Predecessor [Member]	1,054,602				1,054,602
Conversion of preferred stock (in shares) | Predecessor [Member]			6,965,000
Conversion of preferred stock | Predecessor [Member]	(38)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition | Predecessor [Member]				1,511
Stock Issued During Period, Value, Stock Options Exercised | Predecessor [Member]	1,511
Other | Predecessor [Member]		1,266	$ (69)	(1,198)			39
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	49,943
Balance as of end of period (in shares) (Predecessor [Member]) at Sep. 12, 2016			88,218,000
Balance as of end of period (Successor [Member]) at Sep. 12, 2016					0
Balance as of end of period (Predecessor [Member]) at Sep. 12, 2016		0	$ 0	0	0	0	0	0
Balance as of end of period at Sep. 12, 2016	0
Balance as of beginning of period (in shares) (Predecessor [Member]) at Dec. 31, 2015			81,253,000
Balance as of beginning of period (Predecessor [Member]) at Dec. 31, 2015	(915,121)	3,146	$ 628	1,211,088	(2,130,271)	3,440	422	(3,574)
Balance as of end of period (in shares) (Successor [Member]) at Dec. 31, 2016			14,992,000
Balance as of end of period (Successor [Member]) at Dec. 31, 2016	185,548	0	$ 150	190,621	(5,296)	0	73	0
Issuance of Common Stock, Backstop Fee | Successor [Member]	9,059
Issuance of Common Stock, Exchange of Claims | Successor [Member]	$ 131,893
Postconfirmation, Shares outstanding | Successor [Member]	14,992,000
Postconfirmation, Stockholders' Equity | Successor [Member]	$ 190,895		150	190,745	0	0	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of Equity Upon Emergence from Bankruptcy | Predecessor [Member]		(1,880)	(697)	(1,213,797)	1,075,669	(3,440)	(383)	3,574
Cancellation of Equity Upon Emergence from Bankruptcy	882,992
Cancellation of Total Equity Upon Emergence from Bankruptcy | Predecessor [Member]	(140,954)
Preconfirmation, Stockholders' Equity | Predecessor [Member]	(1,035,831)	(1,880)	$ (697)	(1,213,797)	(1,075,669)	(3,440)	(383)	(3,574)
Preconfirmation, Stockholders' Equity	$ (140,954)
Cancellation of Equity Upon Emergence from Bankruptcy, Shares | Predecessor [Member]			(88,218,000)
Postconfirmation, Common Stock - Rights Offering | Successor [Member]			$ 76
Postconfirmation, Additional Paid-in Capital - Rights Offering | Successor [Member]			49,867
Postconfirmation, Common Stock - Backstop Fee | Successor [Member]			5
Postconfirmation, Additional paid-in capital - Backstop Fee | Successor [Member]			$ 9,054
Postconfirmation, Common Stock - Rights Offering, shares | Successor [Member]			7,634,000
Postconfirmation, Common Stock - Backstop Fee, Shares | Successor [Member]			473,000
Postconfirmation, Common Stock - Exchange of Claims,Shares | Successor [Member]			6,885,000
Postconfirmation, Common Stock - Exchange of Claims | Successor [Member]			$ 69
Postconfirmation, Additional paid-in capital - Exchange of Claims | Successor [Member]			$ 131,824
Common Stock, Shares, Outstanding | Predecessor [Member]			0
Common Stock, Shares, Outstanding	14,992,018
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax | Successor [Member]	$ (73)
Balance as of beginning of period (in shares) (Predecessor [Member]) at Sep. 12, 2016			88,218,000
Balance as of beginning of period (Successor [Member]) at Sep. 12, 2016					0
Balance as of beginning of period (Predecessor [Member]) at Sep. 12, 2016		0	$ 0	0	0	0	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) | Successor [Member]	(5,296)				(5,296)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition | Successor [Member]				81
Other | Successor [Member]	132			205	0	0	(73)	0
Balance as of end of period (in shares) (Successor [Member]) at Dec. 31, 2016			14,992,000
Balance as of end of period (Successor [Member]) at Dec. 31, 2016	185,548	0	$ 150	190,621	(5,296)	0	73	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax | Successor [Member]	73
Net income (loss) | Successor [Member]	32,662				32,662
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition | Successor [Member]				3,809
Restricted stock unit vesting (in shares) | Successor [Member]			27,000
Other | Successor [Member]	29			(44)			73
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures | Successor [Member]	(351)			(351)
Balance as of end of period (in shares) (Successor [Member]) at Dec. 31, 2017			15,019,000
Balance as of end of period (Successor [Member]) at Dec. 31, 2017	$ 221,639	$ 0	$ 150	$ 194,123	$ 27,366	$ 0	$ 0	$ 0