Short-Term and Long-Term Debt, Including Capital Leases Credit Facility (Narrative) (Details)
12 Months Ended
Nov. 05, 2015
USD ($)
Dec. 31, 2015
USD ($)
Integer
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Feb. 01, 2015
USD ($)
Debt Instrument [Line Items]          
Debt instrument, interest period   1 month      
Letters of credit outstanding amount   $ 17,211,000 $ 17,511,000    
Line of credit facility, remaining borrowing capacity   $ 142,413,000 149,134,000    
Number of quarters | Integer   4      
Less: portion of Credit Facility classified as short-term   $ (19,958,000) (2,002,000)    
Interest expense, debt   8,983,000 6,812,000 $ 7,191,000  
Interest paid   $ 7,973,000 5,880,000 $ 6,379,000  
Capital stock of Company's and Guarantor's present and future domestic subsidiaries          
Debt Instrument [Line Items]          
Line of credit facility, guarantee obligation, percentage of stock (percent)   100.00%      
Voting stock of present and future first-tier foreign subsidiaries of the Company or Guarantor          
Debt Instrument [Line Items]          
Line of credit facility, guarantee obligation, percentage of stock (percent)   65.00%      
Non-voting stock of present and future first-tier foreign subsidiaries of the Company or Guarantor          
Debt Instrument [Line Items]          
Line of credit facility, guarantee obligation, percentage of stock (percent)   100.00%      
Capital stock of Foreign Borrowers          
Debt Instrument [Line Items]          
Line of credit facility, guarantee obligation, percentage of stock (percent)   100.00%      
Minimum          
Debt Instrument [Line Items]          
Lessee leasing arrangements, capital leases, term of contract   24 months      
Maximum          
Debt Instrument [Line Items]          
Lessee leasing arrangements, capital leases, term of contract   60 months      
UK Borrower | GAB Robins          
Debt Instrument [Line Items]          
Other long-term debt, noncurrent         $ 78,355,000
Credit Facility          
Debt Instrument [Line Items]          
Line of Credit Facility, current borrowing capacity   $ 400,000,000      
Credit Facility   $ 243,667,000 $ 155,002,000    
Credit Facility | London Interbank Offered Rate (LIBOR)          
Debt Instrument [Line Items]          
Debt instrument, basis spread on variable rate (percent)   1.00%      
Credit Facility | Base Rate Loans | Federal Funds Rate          
Debt Instrument [Line Items]          
Debt instrument, basis spread on variable rate (percent)   0.50%      
Credit Facility | Minimum | London Interbank Offered Rate (LIBOR)          
Debt Instrument [Line Items]          
Debt instrument, basis spread on variable rate (percent)   1.50%      
Credit Facility | Minimum | Base Rate          
Debt Instrument [Line Items]          
Debt instrument, basis spread on variable rate (percent)   0.50%      
Credit Facility | Maximum | London Interbank Offered Rate (LIBOR)          
Debt Instrument [Line Items]          
Debt instrument, basis spread on variable rate (percent)   2.25%      
Credit Facility | Maximum | Base Rate          
Debt Instrument [Line Items]          
Debt instrument, basis spread on variable rate (percent)   1.25%      
Credit Facility | UK Borrower          
Debt Instrument [Line Items]          
Line of Credit Facility, current borrowing capacity   $ 185,000,000      
Credit Facility | Canadian Borrower          
Debt Instrument [Line Items]          
Line of Credit Facility, current borrowing capacity   40,000,000      
Credit Facility | Australian Borrower          
Debt Instrument [Line Items]          
Line of Credit Facility, current borrowing capacity   15,000,000      
Letter of credit subfacility          
Debt Instrument [Line Items]          
Line of Credit Facility, current borrowing capacity   $ 100,000,000      
Wells Fargo Bank, National Association | Credit Facility | 2015 Amendment to Credit Agreement          
Debt Instrument [Line Items]          
Debt instrument, covenant, maximum allowable exclusions from EBITDA in remainder of fiscal year $ 27,000,000        
Debt instrument, covenant, maximum allowable exclusions from EBITDA in year two 13,000,000        
Debt instrument, covenant, maximum aggregate allowable exclusions from EBITDA 38,000,000        
Debt instrument, covenant, allowable disposition of immaterial foreign subsidiaries, maximum book value $ 15,000,000        
Debt instrument, covenant, coverage ratio   1.25      
Debt instrument, covenant, leverage ratio in period one 3.75        
Debt instrument, covenant, leverage ratio in period two 3.50        
Debt instrument, covenant, leverage ratio in period three 3.25