Quarterly report pursuant to Section 13 or 15(d)

Basis of Financial Statement Presentation (Details)

v2.4.0.6
Basis of Financial Statement Presentation (Details)
6 Months Ended
Sep. 30, 2012
USD ($)
Sep. 30, 2011
Mar. 31, 2012
USD ($)
Aug. 31, 2006
USD ($)
Aug. 31, 2006
EUR (€)
Sep. 30, 2012
Carrying Value
USD ($)
Mar. 31, 2012
Carrying Value
USD ($)
Sep. 30, 2012
Recurring
USD ($)
Mar. 31, 2012
Recurring
USD ($)
Sep. 30, 2012
Recurring
Level 1
USD ($)
Mar. 31, 2012
Recurring
Level 1
USD ($)
Sep. 30, 2012
Recurring
Level 2
USD ($)
Mar. 31, 2012
Recurring
Level 2
USD ($)
Restricted Cash                          
Guarantee issued by the European bank in conjunction with the establishment of a VAT registration in The Netherlands       $ 1,900,000 € 1,500,000                
Deposits pledged to the European bank       2,100,000 1,700,000                
Fair Value Measurement                          
Money markets           26,239,000 26,215,000 26,239,000 26,215,000 26,239,000 26,215,000    
Long-term debt           361,197,000 347,331,000 362,301,000 362,086,000 360,325,000 358,700,000 1,976,000 3,386,000
Revenue Recognition                          
Period of product warranty 1 year                        
Warranty costs as a percentage of net sales, maximum 1.00% 1.00%                      
Components of inventories                          
Raw materials and supplies 90,403,000   86,845,000                    
Work in process 84,182,000   72,411,000                    
Finished goods 67,594,000   70,122,000                    
Inventory, gross 242,179,000   229,378,000                    
Inventory reserves (17,406,000)   (17,144,000)                    
Inventories, net $ 224,773,000   $ 212,234,000