Long-term Debt - Additional Information (Details) - USD ($) shares in Thousands	1 Months Ended		6 Months Ended
	Feb. 28, 2018	Jan. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Gain on extinguishment of debt			$ 53,000	$ 0
Credit Facility
Debt Instrument [Line Items]
Debt, face amount			20,000,000		$ 5,000,000
Second Lien Notes
Debt Instrument [Line Items]
Debt, face amount			6,965,000		85,239,000
Senior Notes
Debt Instrument [Line Items]
Debt, face amount			1,865,000		1,872,000
Senior Loan Facility
Debt Instrument [Line Items]
Debt, face amount			$ 29,000,000		$ 29,995,000
Senior Loan Facility | Credit Facility
Debt Instrument [Line Items]
Debt instrument extended maturity period	2020-01
Restructuring Support Agreement | Supporting Holders | Secured Debt | Second Lien Notes
Debt Instrument [Line Items]
Percentage of par value of debt owned by holders		85.00%
Exchange Offer | Second Lien Notes and Senior Secured Notes
Debt Instrument [Line Items]
Gain on extinguishment of debt		$ 100,000
Exchange Offer | Secured Debt | Second Lien Notes
Debt Instrument [Line Items]
Debt, face amount		78,000,000
Exchange Offer | Secured Debt | Senior Notes
Debt Instrument [Line Items]
Debt, face amount		$ 7,000
Exchange Offer | Secured Debt | Common Stock | Second Lien Notes and Senior Secured Notes
Debt Instrument [Line Items]
Issuance of preferred stock (in shares)		800
Exchange Offer | Secured Debt | Series A Preferred Stock | Second Lien Notes and Senior Secured Notes
Debt Instrument [Line Items]
Issuance of preferred stock (in shares)		30
Exchange Offer | Secured Debt | Series B Preferred Stock | Second Lien Notes and Senior Secured Notes
Debt Instrument [Line Items]
Issuance of preferred stock (in shares)		900
Exchange Offer | Secured Debt | Series C Warrants | Second Lien Notes and Senior Secured Notes
Debt Instrument [Line Items]
Issuance of preferred stock (in shares)		8,300