v3.4.0.3
Segment Information - Depreciation and Amortization Expense Included in Direct Expenses and Unallocated Selling, General, and Administrative Costs (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Reportable Operating Segments [Member]    
Segment Reporting, Asset Reconciling Item [Line Items]    
Depreciation and Amortization Expenses $ 14,302 $ 15,505
Reportable Operating Segments [Member] | Oil and Gas [Member]    
Segment Reporting, Asset Reconciling Item [Line Items]    
Depreciation and Amortization Expenses 9,918 11,280
Reportable Operating Segments [Member] | Air Medical [Member]    
Segment Reporting, Asset Reconciling Item [Line Items]    
Depreciation and Amortization Expenses 4,256 4,097
Reportable Operating Segments [Member] | Technical Services [Member]    
Segment Reporting, Asset Reconciling Item [Line Items]    
Depreciation and Amortization Expenses 128 128
Unallocated Selling, General and Administrative Expenses [Member]    
Segment Reporting, Asset Reconciling Item [Line Items]    
Depreciation and Amortization Expenses $ 2,671 $ 2,646