Quarterly report pursuant to Section 13 or 15(d)

Goodwill and Other Intangible Assets - Intangible Assets related to Acquisition (Details)

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Goodwill and Other Intangible Assets - Intangible Assets related to Acquisition (Details) - USD ($)
$ in Thousands
 6 Months Ended
Sep. 30, 2016
Mar. 31, 2016
Finite-Lived Intangible Assets [Line Items]    
Intangible Assets, Gross (Excluding Goodwill) $ 158,645 $ 163,984
Finite-Lived Intangible Assets, Accumulated Amortization 65,589 59,986
Intangible Assets, Net (Excluding Goodwill) 93,056 103,998
Trademarks    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Accumulated Amortization 381 237
Industrial Process Insulators, Inc.    
Finite-Lived Intangible Assets [Line Items]    
Intangible Assets, Gross (Excluding Goodwill) 8,589 13,347
Finite-Lived Intangible Assets, Accumulated Amortization 1,448 1,046
Intangible Assets, Net (Excluding Goodwill) 7,141 12,301
Sumac Fabrication Company Limited    
Finite-Lived Intangible Assets [Line Items]    
Intangible Assets, Gross (Excluding Goodwill) 2,778 2,806
Finite-Lived Intangible Assets, Accumulated Amortization 1,114 750
Intangible Assets, Net (Excluding Goodwill) $ 1,664 2,056
Noncompete Agreements [Member] | Industrial Process Insulators, Inc.    
Finite-Lived Intangible Assets [Line Items]    
Amortization period 3 years  
Intangible Assets, Gross (Excluding Goodwill) $ 807 807
Finite-Lived Intangible Assets, Accumulated Amortization 314 179
Intangible Assets, Net (Excluding Goodwill) $ 493 628
Noncompete Agreements [Member] | Sumac Fabrication Company Limited    
Finite-Lived Intangible Assets [Line Items]    
Amortization period 2 years  
Intangible Assets, Gross (Excluding Goodwill) $ 192 194
Finite-Lived Intangible Assets, Accumulated Amortization 144 97
Intangible Assets, Net (Excluding Goodwill) 48 97
Customer Relationships    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Accumulated Amortization $ 59,884 54,913
Customer Relationships | Industrial Process Insulators, Inc.    
Finite-Lived Intangible Assets [Line Items]    
Amortization period 8 years  
Intangible Assets, Gross (Excluding Goodwill) $ 5,962 10,720
Finite-Lived Intangible Assets, Accumulated Amortization 869 715
Intangible Assets, Net (Excluding Goodwill) $ 5,093 10,005
Customer Relationships | Sumac Fabrication Company Limited    
Finite-Lived Intangible Assets [Line Items]    
Amortization period 4 years  
Intangible Assets, Gross (Excluding Goodwill) $ 2,586 2,612
Finite-Lived Intangible Assets, Accumulated Amortization 970 653
Intangible Assets, Net (Excluding Goodwill) $ 1,616 1,959
Trademarks | Industrial Process Insulators, Inc.    
Finite-Lived Intangible Assets [Line Items]    
Amortization period 8 years  
Intangible Assets, Gross (Excluding Goodwill) $ 1,820  
Finite-Lived Intangible Assets, Accumulated Amortization 265  
Intangible Assets, Net (Excluding Goodwill) 1,555  
Developed Technology Rights    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Accumulated Amortization 3,236 2,988
Other Intangible Assets    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Assets, Accumulated Amortization $ 2,088 1,848
Other Intangible Assets | Industrial Process Insulators, Inc.    
Finite-Lived Intangible Assets [Line Items]    
Intangible Assets, Gross (Excluding Goodwill)   1,820
Finite-Lived Intangible Assets, Accumulated Amortization   152
Intangible Assets, Net (Excluding Goodwill)   $ 1,668