Quarterly report pursuant to Section 13 or 15(d)

Changes in Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Detail)

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Changes in Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     $ 114,110  
Other comprehensive income before reclassifications     140 $ (148)
Amounts reclassified from accumulated other comprehensive loss     340 449
Total other comprehensive income $ 256 $ 214 480 301
Ending Balance 113,868   113,868  
Pension and Other Postretirement Benefits Items [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     (8,439) (10,932)
Amounts reclassified from accumulated other comprehensive loss     340 449
Total other comprehensive income     340 449
Ending Balance (8,099) (10,483) (8,099) (10,483)
Foreign Currency Items [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     5 256
Other comprehensive income before reclassifications     140 (148)
Total other comprehensive income     140 (148)
Ending Balance 145 108 145 108
AOCI Attributable to Parent [Member]        
Accumulated Other Comprehensive Income (Loss) [Line Items]        
Beginning balance     (8,434) (10,676)
Ending Balance $ (7,954) $ (10,375) $ (7,954) $ (10,375)