Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Summary of Depreciable Lives for Different Categories of Property Plant and Equipment (Detail)

v3.8.0.1
Summary of Significant Accounting Policies - Summary of Depreciable Lives for Different Categories of Property Plant and Equipment (Detail)
 12 Months Ended
Dec. 31, 2017
Land Drilling Equipment | Minimum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 3 years
Land Drilling Equipment | Maximum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 20 years
Barage Drilling Equipment | Minimum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 3 years
Barage Drilling Equipment | Maximum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 20 years
Drill pipe, rental tools and other | Minimum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 4 years
Drill pipe, rental tools and other | Maximum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 15 years
Buildings and improvements | Minimum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 5 years
Buildings and improvements | Maximum  
Property, Plant and Equipment [Line Items]  
Property, plant and equipment useful life 30 years