Debt - Interest Rates (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Commitment fee percentage	40.00%	40.00%	40.00%	40.00%
First Lien Facility | Minimum
Debt Instrument [Line Items]
Interest rate	5.23%	4.46%	4.77%	3.86%
First Lien Facility | Maximum
Debt Instrument [Line Items]
Interest rate	5.30%	4.52%	5.30%	4.53%
First Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	6.47%	5.65%	6.13%	5.49%
Ultraco Debt Facility | Minimum
Debt Instrument [Line Items]
Interest rate	4.19%		4.19%
Ultraco Debt Facility | Maximum
Debt Instrument [Line Items]
Interest rate	4.25%		4.25%
Ultraco Debt Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	4.55%		4.55%
Second Lien Facility
Debt Instrument [Line Items]
Interest rate	15.00%	15.00%	15.00%	15.00%
Second Lien Facility | Weighted Average
Debt Instrument [Line Items]
Interest rate	17.05%	17.05%	17.05%	17.05%