Quarterly report pursuant to Section 13 or 15(d)

Reportable Segments - Additional Information (Detail)

v3.5.0.2
Reportable Segments - Additional Information (Detail) - Exxon Neftegas Limited [Member]
6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Segment Information [Line Items]    
Percentage of revenue from major customer 39.80% 26.00%
International & Alaska Drilling [Member]    
Segment Information [Line Items]    
Percentage of revenue from major customer 58.40% 44.30%