Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.19.1
Summary of Significant Accounting Policies - Additional Information (Detail)
$ in Thousands
 3 Months Ended 12 Months Ended
Jul. 27, 2018
Dec. 31, 2018
USD ($)
country
Sep. 30, 2018
USD ($)
Jun. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Sep. 30, 2017
USD ($)
Jun. 30, 2017
USD ($)
Mar. 31, 2017
USD ($)
Dec. 31, 2018
USD ($)
country
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Revenue, Major Customer [Line Items]                          
Number of countries entity has operated in since inception (more than) | country   50               50      
Percentage accounted for under the equity method   50.00%               50.00%      
Cash and cash equivalents   $ 48,602       $ 141,549       $ 48,602 $ 141,549    
Restricted cash   10,389       0       10,389 0    
Cash, cash equivalents and restricted cash at end of period   58,991       141,549       58,991 141,549 $ 119,691 $ 134,294
Cash collateral paid in support of letters of credit outstanding                   9,800      
Compensating balance   600               600      
Capitalized interest costs of construction of rigs                   $ 100 0 200  
Consumed and replenished period                   1 year      
Revenues   129,148 $ 123,395 $ 118,603 $ 109,675 116,334 $ 118,308 $ 109,607 $ 98,271 $ 480,821 442,520 427,004  
Deposits in domestic bank   27,500       97,600       27,500 97,600    
Deposits in foreign banks   $ 32,900       $ 45,600       $ 32,900 $ 45,600    
Reverse stock split ratio 15                        
Series A Mandatory Convertible Preferred Stock                          
Revenue, Major Customer [Line Items]                          
Preferred stock, stated interest rate                   7.25% 7.25%    
Reimbursable revenue                          
Revenue, Major Customer [Line Items]                          
Revenues                   $ 54,600 $ 57,800 69,300  
Exxon Neftegas Limited (ENL) | Reimbursable revenue                          
Revenue, Major Customer [Line Items]                          
Revenues                   $ 47,200 $ 50,800 $ 67,000  
Customer Concentration Risk | Sales Revenue, Net | Exxon Neftegas Limited (ENL)                          
Revenue, Major Customer [Line Items]                          
Percentage of revenue from major customer                   25.70% 31.30% 38.70%  
Customer Concentration Risk | Sales Revenue, Net of Reimbursable Revenues | Exxon Neftegas Limited (ENL)                          
Revenue, Major Customer [Line Items]                          
Percentage of revenue from major customer                   17.90% 22.70% 27.50%  
International & Alaska Drilling | Customer Concentration Risk | Sales Revenue, Net | Exxon Neftegas Limited (ENL)                          
Revenue, Major Customer [Line Items]                          
Percentage of revenue from major customer                   58.00% 55.90% 57.50%  
International & Alaska Drilling | Customer Concentration Risk | Sales Revenue, Net of Reimbursable Revenues | Exxon Neftegas Limited (ENL)                          
Revenue, Major Customer [Line Items]                          
Percentage of revenue from major customer                   48.00% 46.10% 45.00%  
Minimum                          
Revenue, Major Customer [Line Items]                          
Estimated Useful Life (Years)                   3 years      
Maximum                          
Revenue, Major Customer [Line Items]                          
Estimated Useful Life (Years)                   6 years