Debt - Interest Rates (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New First Lien Facility
Debt Instrument [Line Items]
Interest rate	5.55%
Commitment fee percentage			40.00%
New First Lien Facility | Minimum
Debt Instrument [Line Items]
Interest rate			4.91%
New First Lien Facility | Maximum
Debt Instrument [Line Items]
Interest rate			5.55%
New First Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	6.18%		5.82%
Ultraco Debt Facility
Debt Instrument [Line Items]
Interest rate	5.25%	4.08%		4.08%
Commitment fee percentage	40.00%		40.00%
Ultraco Debt Facility | Minimum
Debt Instrument [Line Items]
Interest rate			4.64%
Ultraco Debt Facility | Maximum
Debt Instrument [Line Items]
Interest rate			5.25%
Ultraco Debt Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	5.83%		5.56%
First Lien Facility
Debt Instrument [Line Items]
Commitment fee percentage		40.00%		40.00%
First Lien Facility | Minimum
Debt Instrument [Line Items]
Interest rate		4.98%		4.77%
First Lien Facility | Maximum
Debt Instrument [Line Items]
Interest rate		5.15%		5.15%
First Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate		5.58%		5.41%
Second Lien Facility
Debt Instrument [Line Items]
Interest rate		15.00%		15.00%
Second Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate		17.05%		17.05%
Senior Subordinated Notes | Norwegian Bond Debt Facility
Debt Instrument [Line Items]
Interest rate	8.25%		8.25%
Senior Subordinated Notes | Norwegian Bond Debt Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	8.79%		8.79%