| 
                Total assets
             | 
                        
                1.2B
             | 
                        
                1.2B
             | 
                        
                1.3B
             | 
                        
                976.5M
             | 
                    
                
                        | 
                Current assets
             | 
                        
                509.6M
             | 
                        
                544.3M
             | 
                        
                661.9M
             | 
                        
                458.5M
             | 
                    
                
                        | 
                Cash
             | 
                        
                187.8M
             | 
                        
                —
             | 
                        
                255.9M
             | 
                        
                —
             | 
                    
                
                        | 
                Cash equivalents
             | 
                        
                26.9M
             | 
                        
                —
             | 
                        
                34.9M
             | 
                        
                —
             | 
                    
                
                        | 
                Cash and cash equivalents
             | 
                        
                214.7M
             | 
                        
                310.0M
             | 
                        
                290.8M
             | 
                        
                326.1M
             | 
                    
                
                        | 
                Other short term investments
             | 
                        
                140.2M
             | 
                        
                95.2M
             | 
                        
                225.3M
             | 
                        
                —
             | 
                    
                
                        | 
                Accounts receivable
             | 
                        
                64.4M
             | 
                        
                65.6M
             | 
                        
                68.1M
             | 
                        
                77.5M
             | 
                    
                
                        | 
                Other receivables
             | 
                        
                14.0M
             | 
                        
                3.6M
             | 
                        
                9.1M
             | 
                        
                3.4M
             | 
                    
                
                        | 
                Inventory
             | 
                        
                47.1M
             | 
                        
                40.2M
             | 
                        
                43.4M
             | 
                        
                39.1M
             | 
                    
                
                        | 
                Prepaid assets
             | 
                        
                6.4M
             | 
                        
                8.8M
             | 
                        
                4.5M
             | 
                        
                6.9M
             | 
                    
                
                        | 
                Restricted cash
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Assets held for sale
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Hedging assets
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Other current assets
             | 
                        
                22.8M
             | 
                        
                20.9M
             | 
                        
                20.7M
             | 
                        
                5.5M
             | 
                    
                
                        | 
                Non current assets
             | 
                        
                651.0M
             | 
                        
                634.2M
             | 
                        
                595.1M
             | 
                        
                518.0M
             | 
                    
                
                        | 
                Properties
             | 
                        
                143.0M
             | 
                        
                246.4M
             | 
                        
                143.6M
             | 
                        
                261.6M
             | 
                    
                
                        | 
                Land and improvements
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Machinery furniture equipment
             | 
                        
                374.7M
             | 
                        
                —
             | 
                        
                374.6M
             | 
                        
                —
             | 
                    
                
                        | 
                Construction in progress
             | 
                        
                296.4M
             | 
                        
                266.5M
             | 
                        
                211.9M
             | 
                        
                142.2M
             | 
                    
                
                        | 
                Leases
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Accumulated depreciation
             | 
                        
                -279.6M
             | 
                        
                —
             | 
                        
                -262.9M
             | 
                        
                —
             | 
                    
                
                        | 
                Goodwill
             | 
                        
                47.9M
             | 
                        
                48.2M
             | 
                        
                48.6M
             | 
                        
                48.9M
             | 
                    
                
                        | 
                Investment properties
             | 
                        
                98.7K
             | 
                        
                98.7K
             | 
                        
                103.6K
             | 
                        
                91.3K
             | 
                    
                
                        | 
                Financial assets
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Intangible assets
             | 
                        
                47.9M
             | 
                        
                48.2M
             | 
                        
                48.6M
             | 
                        
                48.9M
             | 
                    
                
                        | 
                Investments and advances
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Other non current assets
             | 
                        
                45.2M
             | 
                        
                49.8M
             | 
                        
                56.8M
             | 
                        
                47.1M
             | 
                    
                
                        | 
                Total liabilities
             | 
                        
                243.1M
             | 
                        
                250.8M
             | 
                        
                324.4M
             | 
                        
                237.9M
             | 
                    
                
                        | 
                Current liabilities
             | 
                        
                177.2M
             | 
                        
                184.5M
             | 
                        
                257.7M
             | 
                        
                234.6M
             | 
                    
                
                        | 
                Accounts payable
             | 
                        
                167.5M
             | 
                        
                175.0M
             | 
                        
                212.7M
             | 
                        
                225.0M
             | 
                    
                
                        | 
                Accrued expenses
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Short term debt
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Deferred revenue
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Tax payable
             | 
                        
                702.1K
             | 
                        
                675.7K
             | 
                        
                693.1K
             | 
                        
                636.3K
             | 
                    
                
                        | 
                Pensions
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Other current liabilities
             | 
                        
                357.2K
             | 
                        
                257.9K
             | 
                        
                297.1K
             | 
                        
                178.2K
             | 
                    
                
                        | 
                Non current liabilities
             | 
                        
                65.9M
             | 
                        
                66.3M
             | 
                        
                66.7M
             | 
                        
                3.3M
             | 
                    
                
                        | 
                Long term provisions
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Long term debt
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Provision for risks and charges
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Deferred liabilities
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Derivative product liabilities
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Other non current liabilities
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Shareholders equity
             | 
                        
                
             | 
                        
                
             | 
                        
                
             | 
                        
                
             | 
                    
                
                        | 
                Common stock
             | 
                        
                95.7M
             | 
                        
                95.7M
             | 
                        
                95.7M
             | 
                        
                87.9M
             | 
                    
                
                        | 
                Retained earnings
             | 
                        
                280.6M
             | 
                        
                290.6M
             | 
                        
                295.5M
             | 
                        
                308.3M
             | 
                    
                
                        | 
                Other shareholders equity
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Total shareholders equity
             | 
                        
                917.5M
             | 
                        
                927.7M
             | 
                        
                932.6M
             | 
                        
                738.6M
             | 
                    
                
                        | 
                Additional paid in capital
             | 
                        
                486.9M
             | 
                        
                —
             | 
                        
                486.9M
             | 
                        
                —
             | 
                    
                
                        | 
                Treasury stock
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                        
                —
             | 
                    
                
                        | 
                Minority interest
             | 
                        
                1.3M
             | 
                        
                1.4M
             | 
                        
                1.5M
             | 
                        
                1.7M
             |