v3.3.1.900
Business Segments and Geographic Areas - Schedule of Accounts Receivable and Revenue by Major Customers by Reporting Segments (Detail)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Customer Concentration Risk [Member] | Oil and Gas [Member] | Sales Revenue, Segment [Member] | Customer A [Member]      
Revenue, Major Customer [Line Items]      
Concentration risk, percentage 15.00% 17.00% 15.00%
Customer Concentration Risk [Member] | Oil and Gas [Member] | Sales Revenue, Segment [Member] | Customer B [Member]      
Revenue, Major Customer [Line Items]      
Concentration risk, percentage 11.00% 13.00% 13.00%
Customer Concentration Risk [Member] | Air Medical and Technical Services [Member] | Sales Revenue, Segment [Member] | Customer C [Member]      
Revenue, Major Customer [Line Items]      
Concentration risk, percentage 9.00% 10.00% 17.00%
Concentration of Credit Risk [Member] | Oil and Gas [Member] | Accounts Receivable [Member] | Customer A [Member]      
Revenue, Major Customer [Line Items]      
Concentration risk, percentage 6.00% 7.00%  
Concentration of Credit Risk [Member] | Oil and Gas [Member] | Accounts Receivable [Member] | Customer B [Member]      
Revenue, Major Customer [Line Items]      
Concentration risk, percentage 9.00% 12.00%  
Concentration of Credit Risk [Member] | Air Medical and Technical Services [Member] | Accounts Receivable [Member] | Customer C [Member]      
Revenue, Major Customer [Line Items]      
Concentration risk, percentage 15.00% 20.00%