v3.5.0.2
Segment Information - Depreciation and Amortization Expense Included in Direct Expenses and Unallocated Selling, General, and Administrative Costs (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Reportable Operating Segments [Member]        
Segment Reporting, Asset Reconciling Item [Line Items]        
Depreciation and Amortization Expenses $ 15,313 $ 15,205 $ 29,614 $ 30,711
Reportable Operating Segments [Member] | Oil and Gas [Member]        
Segment Reporting, Asset Reconciling Item [Line Items]        
Depreciation and Amortization Expenses 10,024 10,323 19,942 21,603
Reportable Operating Segments [Member] | Air Medical [Member]        
Segment Reporting, Asset Reconciling Item [Line Items]        
Depreciation and Amortization Expenses 5,132 4,750 9,387 8,848
Reportable Operating Segments [Member] | Technical Services [Member]        
Segment Reporting, Asset Reconciling Item [Line Items]        
Depreciation and Amortization Expenses 157 132 285 260
Unallocated Selling, General and Administrative Expenses [Member]        
Segment Reporting, Asset Reconciling Item [Line Items]        
Depreciation and Amortization Expenses $ 2,476 $ 3,155 $ 5,147 $ 5,801