Quarterly report pursuant to Section 13 or 15(d)

Financing Arrangements - Narrative (Details)

v3.8.0.1
Financing Arrangements - Narrative (Details)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Oct. 31, 2017
USD ($)
Oct. 02, 2017
USD ($)
Jan. 06, 2017
USD ($)
Dec. 31, 2017
USD ($)
Oct. 31, 2017
USD ($)
Sep. 30, 2017
USD ($)
Jun. 30, 2017
USD ($)
May 31, 2017
USD ($)
Apr. 30, 2017
Feb. 28, 2015
USD ($)
d
$ / shares
Sep. 30, 2017
USD ($)
Jun. 30, 2017
Mar. 31, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Jul. 27, 2016
USD ($)
Oct. 18, 2013
USD ($)
Debt Instrument [Line Items]                                      
Loss from extinguishment of debt                     $ 0   $ 14,500,000 $ 0 $ (14,389,000) $ 0      
Capital lease obligations incurred                                 $ 1,000,000    
Maximum lease payments           $ 1,932,000         1,932,000       1,932,000   $ 2,000,000    
Other loans payable           $ 400,000         $ 400,000       $ 400,000        
IFES Acquisition Corp Limited                                      
Debt Instrument [Line Items]                                      
Effective interest rate percentage           1.75%         1.75%       1.75%        
EMC Acquisition                                      
Debt Instrument [Line Items]                                      
Capital lease obligation assumed                                   $ 1,100,000  
Line of Credit                                      
Debt Instrument [Line Items]                                      
Borrowings outstanding under facility letters           $ 700,000         $ 700,000       $ 700,000        
Line of Credit                                      
Debt Instrument [Line Items]                                      
Maximum borrowing capacity     $ 585,000,000                                
Letters of credit outstanding           $ 7,100,000         $ 7,100,000       $ 7,100,000        
Percentage of outstanding equity in foreign subsidiaries pledged as collateral                                 65.00%    
Line of Credit | Secured Debt                                      
Debt Instrument [Line Items]                                      
Maximum borrowing capacity     $ 500,000,000                                
Periodic payment, period one     0.25%         0.625%                      
Maximum consolidated EBITDA               $ 5,000,000                      
Periodic payment period two               1.25%                      
Consent fee percentage           0.25% 0.25% 1.00%     0.25% 0.25%     0.25%        
Consent fee paid           $ 1,400,000 $ 3,900,000 $ 5,600,000                      
Fee as percentage of outstanding balance if 12/31/2016 financials not filed by June 30, 2017             0.25%         0.25%              
Fee for failure to report, second deadline             0.25%         0.25%              
Line of Credit | Revolving Credit Facility                                      
Debt Instrument [Line Items]                                      
Maximum borrowing capacity     $ 85,000,000                                
Line of Credit | Letters of Credit                                      
Debt Instrument [Line Items]                                      
Maximum borrowing capacity     $ 15,000,000                                
Letters of credit outstanding           5,900,000         $ 5,900,000       $ 5,900,000        
Convertible senior notes                                      
Debt Instrument [Line Items]                                      
Debt instrument, face amount           $ 82,500,000       $ 82,500,000 $ 82,500,000       $ 82,500,000   $ 82,500,000    
Stated interest rate           2.75%       2.75% 2.75%       2.75%        
Conversion ratio                   0.0539084                  
Conversion price (in usd per share) | $ / shares                   $ 18.55                  
Convertible debt           $ 69,500,000         $ 69,500,000       $ 69,500,000   69,000,000    
Equity component of convertible debt           $ 13,000,000         $ 13,000,000       $ 13,000,000        
Increase in stated rate, first ninety days                 0.25%                    
Increase in stated rate, second ninety days                 0.50%                    
Convertible senior notes | Liability component                                      
Debt Instrument [Line Items]                                      
Debt issuance costs                   $ 1,800,000                  
Convertible senior notes | Additional paid-in capital                                      
Debt Instrument [Line Items]                                      
Debt issuance costs                   $ 300,000                  
Convertible senior notes | If company undergoes a fundamental change                                      
Debt Instrument [Line Items]                                      
Redemption price percentage                   100.00%                  
Convertible senior notes | On or after February 20, 2019                                      
Debt Instrument [Line Items]                                      
Percent of stock price to trigger conversion                   130.00%                  
Consecutive trading days                   30 days                  
Trading days | d                   20                  
Convertible senior notes | On or after February 20, 2022                                      
Debt Instrument [Line Items]                                      
Redemption price percentage                   100.00%                  
Convertible senior notes | Redemption scenario one | After March 31, 2015                                      
Debt Instrument [Line Items]                                      
Percent of stock price to trigger conversion                   130.00%                  
Convertible senior notes | Redemption scenario two | After March 31, 2015                                      
Debt Instrument [Line Items]                                      
Percent of stock price to trigger conversion                   98.00%                  
Consecutive business days | d                   5                  
Consecutive trading days                   5 days                  
Commercial Mortgage Loan | Mortgage letters maturing October 2032 | IFES Acquisition Corp Limited                                      
Debt Instrument [Line Items]                                      
Business acquisition, assumed indebtedness                                     $ 1,100,000
Accrued interest on mortgage letters                                 $ 0    
Adjusted Base Eurocurrency Rate | Line of Credit | Secured Debt                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     6.00%         7.00%                      
Adjusted Base Eurocurrency Rate | Line of Credit | Revolving Credit Facility                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     6.00%         7.00%                      
Adjusted Base Eurocurrency Rate | Line of Credit | Revolving Credit Facility | Minimum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     5.50%                 6.50%              
Adjusted Base Eurocurrency Rate | Line of Credit | Revolving Credit Facility | Maximum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     6.00%                 7.00%              
Base Rate | Line of Credit | Secured Debt                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     5.00%         6.00%                      
Base Rate | Line of Credit | Revolving Credit Facility                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     5.00%         6.00%                      
Base Rate | Line of Credit | Revolving Credit Facility | Minimum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     4.50%                 5.50%              
Base Rate | Line of Credit | Revolving Credit Facility | Maximum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate     5.00%                 6.00%              
Subsequent Event | Line of Credit | Secured Debt                                      
Debt Instrument [Line Items]                                      
Consent fee percentage 0.25%     0.05% 0.25%                            
Consent fee paid       $ 231,000 $ 1,400,000                            
Prepayment premium period one   2.00%                                  
Prepayment premium period two   1.00%                                  
Estimated covenant revenue range $ 5,000,000 $ 5,000,000                                  
Subsequent Event | Adjusted Base Eurocurrency Rate | Line of Credit | Secured Debt                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 7.50% 7.25%                                  
Subsequent Event | Adjusted Base Eurocurrency Rate | Line of Credit | Revolving Credit Facility                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 7.50% 7.25%                                  
Subsequent Event | Adjusted Base Eurocurrency Rate | Line of Credit | Revolving Credit Facility | Minimum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 7.00% 6.75%                                  
Subsequent Event | Adjusted Base Eurocurrency Rate | Line of Credit | Revolving Credit Facility | Maximum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 7.50% 7.25%                                  
Subsequent Event | Base Rate | Line of Credit | Secured Debt                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 6.50% 6.25%                                  
Subsequent Event | Base Rate | Line of Credit | Revolving Credit Facility                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 6.50% 6.25%                                  
Subsequent Event | Base Rate | Line of Credit | Revolving Credit Facility | Minimum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 6.00% 5.75%                                  
Subsequent Event | Base Rate | Line of Credit | Revolving Credit Facility | Maximum                                      
Debt Instrument [Line Items]                                      
Basis spread on variable rate 6.50% 6.25%