Quarterly report pursuant to Section 13 or 15(d)

Goodwill and Other Intangible Assets -Narrative (Details)

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Goodwill and Other Intangible Assets -Narrative (Details) - USD ($)
 3 Months Ended 6 Months Ended
Jul. 31, 2015
Apr. 01, 2015
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Mar. 31, 2016
Goodwill [Line Items]              
Amortization of intangible assets     $ 3,025,000 $ 3,288,000 $ 5,841,000 $ 6,184,000  
Goodwill     123,958,000   123,958,000   $ 121,510,000
Intangible Assets, Net (Excluding Goodwill)     93,056,000   $ 93,056,000   103,998,000
Industrial Process Insulators, Inc.              
Goodwill [Line Items]              
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life         7 years 1 month 28 days    
Amortization of intangible assets         $ 299,000    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Held in Escrow     4,006,000   4,006,000    
Business Acquisition, Percentage of Voting Interests Acquired 100.00%            
Goodwill $ 13,249,000   13,249,000   13,249,000    
Fair value of total consideration transferred $ 21,750,000            
Intangible Assets, Net (Excluding Goodwill)     7,141,000   $ 7,141,000   12,301,000
Sumac Fabrication Company Limited              
Goodwill [Line Items]              
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life         3 years 7 months 6 days    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Held in Escrow     543,000   $ 543,000    
Business Acquisition, Percentage of Voting Interests Acquired   75.00%          
Payments to Acquire Businesses, Gross   $ 10,956,000          
Debt Instrument, face amount   5,905,000          
Goodwill   7,992,000 7,717,000   7,717,000    
Fair value of total consideration transferred   10,956,000          
Intangible Assets, Net (Excluding Goodwill)     1,664,000   1,664,000   $ 2,056,000
Minimum | Canadian Dollar | Sumac Fabrication Company Limited              
Goodwill [Line Items]              
Debt Instrument, Maturity Payment Amount   0          
Maximum | Canadian Dollar | Sumac Fabrication Company Limited              
Goodwill [Line Items]              
Debt Instrument, Maturity Payment Amount   $ 7,500,000          
Canada              
Goodwill [Line Items]              
Amortization of intangible assets     890,000 $ 996,000 1,791,000 $ 2,005,000  
Canada | Sumac Fabrication Company Limited              
Goodwill [Line Items]              
Debt Instrument, face amount     5,905,000   5,905,000    
Canada | CHS Transactions [Member]              
Goodwill [Line Items]              
Goodwill     36,330,000   36,330,000    
Intangible Assets, Net (Excluding Goodwill)     $ 24,285,000   $ 24,285,000