Debt - Interest Rates (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Ultraco Debt Facility
Debt Instrument [Line Items]
Commitment fee percentage	40.00%
Ultraco Debt Facility | Minimum
Debt Instrument [Line Items]
Interest rate during period	4.64%	4.19%
Ultraco Debt Facility | Maximum
Debt Instrument [Line Items]
Interest rate during period	5.76%	4.28%
Ultraco Debt Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate during period	5.58%	4.71%
New First Lien Facility
Debt Instrument [Line Items]
Interest rate during period		4.83%
Commitment fee percentage	40.00%
New First Lien Facility | Minimum
Debt Instrument [Line Items]
Interest rate during period	4.91%
New First Lien Facility | Maximum
Debt Instrument [Line Items]
Interest rate during period	5.89%
New First Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate during period	6.12%	5.21%
First Lien Facility
Debt Instrument [Line Items]
Commitment fee percentage		40.00%
First Lien Facility | Minimum
Debt Instrument [Line Items]
Interest rate during period		4.77%	3.86%
First Lien Facility | Maximum
Debt Instrument [Line Items]
Interest rate during period		5.35%	4.99%
First Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate during period		6.18%	6.83%
Second Lien Facility
Debt Instrument [Line Items]
Interest rate during period		15.00%	15.00%
Second Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate during period		17.05%	17.05%
Bond Debt | Norwegian Bond Debt
Debt Instrument [Line Items]
Interest rate during period	8.25%	8.25%
Bond Debt | Norwegian Bond Debt | Weighted Average
Debt Instrument [Line Items]
Interest rate during period	8.91%	8.84%