Related Parties - Additional Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Airplane Services
Related Party Transaction [Line Items]
Related party transactions	$ 0.9	$ 1.2	$ 1.0
Directional Drilling Services
Related Party Transaction [Line Items]
Related party transactions	0.2	0.2	0.7
Minimum | Marine Transportation and Logistic Services
Related Party Transaction [Line Items]
Related party transactions	$ 0.2	$ 0.2	$ 0.2