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Segment Breakdown of Goodwill (Detail) - USD ($)
$ in Thousands
Dec. 31, 2017
Mar. 31, 2017
Segment Reporting Information [Line Items]    
Goodwill $ 205,211 $ 198,370
Cement [Member]    
Segment Reporting Information [Line Items]    
Goodwill 74,214 74,214
Gypsum Wallboard [Member]    
Segment Reporting Information [Line Items]    
Goodwill 116,618 116,618
Paperboard [Member]    
Segment Reporting Information [Line Items]    
Goodwill 7,538 $ 7,538
Corporate and Other [Member]    
Segment Reporting Information [Line Items]    
Goodwill $ 6,841