Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	IPO [Member]	Private Placement [Member]	Public Offering [Member]	Common Stock [Member]	Common Stock [Member] IPO [Member]	Common Stock [Member] Private Placement [Member]	Common Stock [Member] Public Offering [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] IPO [Member]	Additional Paid-in Capital [Member] Private Placement [Member]	Additional Paid-in Capital [Member] Public Offering [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balances at Dec. 31, 2013	$ 667,971				$ 1,215				$ 721,757					$ (56,169)	$ 1,168
Beginning Balance, shares at Dec. 31, 2013					121,533,408
Capital contributions	124,667				$ 170				124,497
Capital Contributions, shares					16,966,592
Stock-based compensation	256								256
Shares of common stock issued, value		$ 544,709				$ 215				$ 544,494
Shares of common stock issued, shares						21,500,000
Issuance of restricted stock, shares					31,115
Pension obligation adjustment, net of tax	(1,716)														(1,716)
Net loss	(183,176)													(183,176)
Ending Balances at Dec. 31, 2014	1,152,711				$ 1,600				1,391,004					(239,345)	(548)
Ending Balance, shares at Dec. 31, 2014					160,031,115
Stock-based compensation	4,635								4,635
Shares of common stock issued, value			$ 434,070				$ 625				$ 433,445
Shares of common stock issued, shares							62,500,000
Issuance of restricted stock					$ 2				(2)
Issuance of restricted stock, shares					143,155
Pension obligation adjustment, net of tax	548														$ 548
Net loss	(971,410)													(971,410)
Ending Balances at Dec. 31, 2015	620,554				$ 2,227				1,829,082					(1,210,755)
Ending Balance, shares at Dec. 31, 2015					222,674,270
Stock-based compensation	6,216								6,216
Shares of common stock issued, value				$ 123,813				$ 375				$ 123,438
Shares of common stock issued, shares								37,500,000
Issuance of restricted stock					$ 2				(2)
Issuance of restricted stock, shares					149,448
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings	(61)				$ 3				(3)				$ (61)
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings, shares					268,175
Net loss	(203,806)													(203,806)
Ending Balances at Dec. 31, 2016	$ 546,716				$ 2,607				$ 1,958,731				$ (61)	$ (1,414,561)
Ending Balance, shares at Dec. 31, 2016					260,591,893