Financing arrangements (Details) | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Sep. 30, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2014 |
Interest rate swap | Revolving Credit Facility | Loans Payable [Member] | Notes Payable, Other Payables [Member] | Notes Payable, Other Payables [Member] | Domestic Credit Facility | Domestic Credit Facility | Revolving Credit Facility | Commercial bank in the Netherlands | Commercial bank in the Netherlands | Commercial bank in Belgium | Commercial bank in Belgium | Commercial bank in Belgium | Commercial bank in Belgium | Commercial bank in Belgium | Commercial bank in Belgium | Commercial bank in Belgium | Commercial bank in Belgium | Prime Rate | Prime Rate | LIBOR | LIBOR | Tier One | Tier One | Tier Two | Tier Two | Tier Three | Tier Three |
| | USD ($) | USD ($) | EUR (€) | Revolving Credit Facility | Credit sub-facility standby letters of credit | Credit sub-facility standby letters of credit | Credit sub-facility standby letters of credit | Credit sub-facility standby letters of credit | USD ($) | EUR (€) | Line of Credit | Line of Credit | Outstanding performance guarantees | Outstanding performance guarantees | Commercial Loan | Commercial Loan | Minimum [Member] | Maximum [Member] | Revolving credit facility term loan | Domestic Credit Facility | Prime Rate | LIBOR | Prime Rate | LIBOR | Prime Rate | LIBOR |
| | | | | USD ($) | USD ($) | USD ($) | USD ($) | EUR (€) | | | USD ($) | EUR (€) | USD ($) | EUR (€) | USD ($) | EUR (€) | Commercial bank in Belgium | Commercial bank in Belgium | | Revolving Credit Facility | Domestic Credit Facility | Domestic Credit Facility | Domestic Credit Facility | Domestic Credit Facility | Domestic Credit Facility | Domestic Credit Facility |
| | | | | | | | | | | | | | | | | | Line of Credit | Line of Credit | | | Revolving Credit Facility | Revolving Credit Facility | Revolving Credit Facility | Revolving Credit Facility | Revolving Credit Facility | Revolving Credit Facility |
Line of Credit Facility [Line Items] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Maximum borrowing capacity | | | | | | | $15,000,000 | $6,000,000 | | $3,643,500 | € 3,000,000 | $3,300,000 | € 2,700,000 | $972,000 | € 800,000 | $607,000 | € 500,000 | $1,700,000 | € 1,400,000 | | | | | | | | | | |
Line of Credit Facility, Interest Rate During Period | | | | | | | | | | | | | | | | | | | | 2.91% | 3.98% | | | | | | | | |
Maturity date | | | 31-Mar-16 | 2-Jan-24 | | | | | | | | | | | | | | | | | | | | | | | | | |
Description of variable rate basis | | | | | | | | | | | | | | | | | | | | | | | LIBOR | | | | | | |
Basis spread on variable rate | | | | | | | | | | | | | | | | | | | | 1.25% | | 1.40% | | 0.75% | 2.25% | 1.00% | 2.50% | 1.25% | 2.75% |
Interest rate (in hundredths) | | | | | | | 2.92% | | | | | | | 8.50% | 8.50% | | | | | | | | | | | | | | |
Outstanding at the end of the period | | | | | | | | 954,000 | 0 | | | | | 900,000 | 700,000 | | 0 | | | | | | | | | | | | |
Term on debt | | | | 15 years | | | | | | | | | | | | | | | | | | | | | | | | | |
Loan amount | | | | 6,400,000 | | | | | | | | | | | | | | | | | | | | | | | | | |
Long-term Debt, Gross | | | | $4,400,000 | $94,000 | € 78,000 | | | | | | | | | | | | | | | | | | | | | | | |
Fixed interest rate (in hundredths) | | 4.27% | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Interest rate | 4.99% | | | | | | | | | | | | | | | | | | | | | | | | | | | | |