| 
                Total assets
             | 
                        
                490.7M
             | 
                        
                497.1M
             | 
                        
                503.3M
             | 
                        
                505.9M
             | 
                    
                
                        | 
                Current assets
             | 
                        
                361.1M
             | 
                        
                362.6M
             | 
                        
                371.1M
             | 
                        
                387.0M
             | 
                    
                
                        | 
                Cash
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Cash equivalents
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Cash and cash equivalents
             | 
                        
                107.9M
             | 
                        
                98.4M
             | 
                        
                97.1M
             | 
                        
                104.3M
             | 
                    
                
                        | 
                Other short term investments
             | 
                        
                29.2M
             | 
                        
                39.4M
             | 
                        
                38.9M
             | 
                        
                44.0M
             | 
                    
                
                        | 
                Accounts receivable
             | 
                        
                57.9M
             | 
                        
                64.3M
             | 
                        
                52.9M
             | 
                        
                53.2M
             | 
                    
                
                        | 
                Other receivables
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Inventory
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Prepaid assets
             | 
                        
                43.4M
             | 
                        
                38.6M
             | 
                        
                53.8M
             | 
                        
                46.6M
             | 
                    
                
                        | 
                Restricted cash
             | 
                        
                90.9M
             | 
                        
                91.2M
             | 
                        
                101.0M
             | 
                        
                116.3M
             | 
                    
                
                        | 
                Assets held for sale
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Hedging assets
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Other current assets
             | 
                        
                27.6M
             | 
                        
                30.8M
             | 
                        
                23.5M
             | 
                        
                18.9M
             | 
                    
                
                        | 
                Non current assets
             | 
                        
                129.6M
             | 
                        
                134.5M
             | 
                        
                132.2M
             | 
                        
                118.9M
             | 
                    
                
                        | 
                Properties
             | 
                        
                44.2M
             | 
                        
                48.0M
             | 
                        
                41.4M
             | 
                        
                38.7M
             | 
                    
                
                        | 
                Land and improvements
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Machinery furniture equipment
             | 
                        
                —
             | 
                        
                156.9M
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Construction in progress
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Leases
             | 
                        
                —
             | 
                        
                1.9M
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Accumulated depreciation
             | 
                        
                —
             | 
                        
                -162.8M
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Goodwill
             | 
                        
                61.6M
             | 
                        
                62.4M
             | 
                        
                63.0M
             | 
                        
                37.1M
             | 
                    
                
                        | 
                Investment properties
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Financial assets
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Intangible assets
             | 
                        
                9.1M
             | 
                        
                9.6M
             | 
                        
                10.0M
             | 
                        
                6.9M
             | 
                    
                
                        | 
                Investments and advances
             | 
                        
                6.9M
             | 
                        
                7.4M
             | 
                        
                7.3M
             | 
                        
                8.4M
             | 
                    
                
                        | 
                Other non current assets
             | 
                        
                43.2M
             | 
                        
                47.0M
             | 
                        
                47.0M
             | 
                        
                49.8M
             | 
                    
                
                        | 
                Total liabilities
             | 
                        
                194.6M
             | 
                        
                199.2M
             | 
                        
                208.7M
             | 
                        
                210.5M
             | 
                    
                
                        | 
                Current liabilities
             | 
                        
                185.4M
             | 
                        
                188.0M
             | 
                        
                197.1M
             | 
                        
                205.0M
             | 
                    
                
                        | 
                Accounts payable
             | 
                        
                31.7M
             | 
                        
                29.1M
             | 
                        
                27.8M
             | 
                        
                23.8M
             | 
                    
                
                        | 
                Accrued expenses
             | 
                        
                107.4M
             | 
                        
                101.0M
             | 
                        
                118.3M
             | 
                        
                122.4M
             | 
                    
                
                        | 
                Short term debt
             | 
                        
                2.9M
             | 
                        
                —
             | 
                        
                2.9M
             | 
                        
                2.4M
             | 
                    
                
                        | 
                Deferred revenue
             | 
                        
                119.0M
             | 
                        
                122.3M
             | 
                        
                134.2M
             | 
                        
                150.5M
             | 
                    
                
                        | 
                Tax payable
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Pensions
             | 
                        
                —
             | 
                        
                16.1M
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Other current liabilities
             | 
                        
                31.8M
             | 
                        
                36.6M
             | 
                        
                32.2M
             | 
                        
                28.4M
             | 
                    
                
                        | 
                Non current liabilities
             | 
                        
                9.2M
             | 
                        
                11.2M
             | 
                        
                11.6M
             | 
                        
                5.5M
             | 
                    
                
                        | 
                Long term provisions
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Long term debt
             | 
                        
                8.4M
             | 
                        
                4.6M
             | 
                        
                5.3M
             | 
                        
                5.0M
             | 
                    
                
                        | 
                Provision for risks and charges
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Deferred liabilities
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Derivative product liabilities
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Other non current liabilities
             | 
                        
                824K
             | 
                        
                6.6M
             | 
                        
                6.3M
             | 
                        
                467K
             | 
                    
                
                        | 
                Shareholders equity
             | 
                        
                
             | 
                        
                
             | 
                        
                
             | 
                        
                
             | 
                    
                
                        | 
                Common stock
             | 
                        
                311K
             | 
                        
                310K
             | 
                        
                310K
             | 
                        
                300K
             | 
                    
                
                        | 
                Retained earnings
             | 
                        
                -4.8M
             | 
                        
                -15.8M
             | 
                        
                -33.1M
             | 
                        
                -37.8M
             | 
                    
                
                        | 
                Other shareholders equity
             | 
                        
                -11.7M
             | 
                        
                -11.3M
             | 
                        
                -11.3M
             | 
                        
                -11.1M
             | 
                    
                
                        | 
                Total shareholders equity
             | 
                        
                -16.2M
             | 
                        
                -26.8M
             | 
                        
                -44.1M
             | 
                        
                -48.6M
             | 
                    
                
                        | 
                Additional paid in capital
             | 
                        
                297.2M
             | 
                        
                296.0M
             | 
                        
                295.9M
             | 
                        
                278.6M
             | 
                    
                
                        | 
                Treasury stock
             | 
                        
                106.9M
             | 
                        
                101.6M
             | 
                        
                88.2M
             | 
                        
                69.4M
             | 
                    
                
                        | 
                Minority interest
             | 
                        
                14.7M
             | 
                        
                13.2M
             | 
                        
                12.6M
             | 
                        
                12.4M
             |