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Segment Breakdown of Goodwill (Detail) - USD ($) $ in Thousands | Mar. 31, 2018 | 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 |

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- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975 + Details
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