Debt - Interest Rates (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New First Lien Facility
Debt Instrument [Line Items]
Interest rate	5.82%
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			5.82%
New First Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	6.45%		6.03%
Ultraco Debt Facility
Debt Instrument [Line Items]
Interest rate		4.55%
Commitment fee percentage	40.00%		40.00%
Ultraco Debt Facility | Minimum
Debt Instrument [Line Items]
Interest rate	5.28%	4.19%	4.64%
Ultraco Debt Facility | Maximum
Debt Instrument [Line Items]
Interest rate	5.34%	4.25%	5.34%
Ultraco Debt Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	5.70%		5.60%
First Lien Facility
Debt Instrument [Line Items]
Commitment fee percentage		40.00%		40.00%
First Lien Facility | Minimum
Debt Instrument [Line Items]
Interest rate		5.23%		4.77%
First Lien Facility | Maximum
Debt Instrument [Line Items]
Interest rate		5.30%		5.30%
First Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate		6.47%		6.13%
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	8.80%		8.82%