Financial Information Related to Operations by Segment (Detail) $ in Thousands	3 Months Ended
Jun. 30, 2018 USD ($) kT	Jun. 30, 2017 USD ($) kT	Mar. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Revenue	$ 393,756	$ 366,121
Less: Joint Venture Revenue	(27,264)	(28,170)
Operating Earnings	100,885	95,935
Corporate General and Administrative Expense	(8,003)	(9,679)
Litigation Settlements and Losses	(1,800)
Other Non-Operating Income	571	757
Earnings Before Interest and Income Taxes	91,653	87,013
Interest Expense, Net	(6,632)	(7,483)
Earnings before Income Taxes	85,021	79,530
Capital Expenditures	53,073	16,160
Depreciation, Depletion and Amortization	29,850	28,947
Identifiable Assets	2,426,975		$ 2,368,003
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	442,876	416,990
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(21,856)	(22,699)
Other [Member]
Segment Reporting Information [Line Items]
Operating Earnings	284
Capital Expenditures	340	45
Identifiable Assets	164,817		104,367
Cement [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	$ 186,788	$ 182,935
Cement Sales Volume \| kT	1,511	1,511
Operating Earnings	$ 37,334	$ 43,181
Capital Expenditures	19,613	7,718
Depreciation, Depletion and Amortization	12,921	$ 12,479
Identifiable Assets	$ 1,225,783		1,247,504
Cement [Member] \| Operating Segments [Member] \| Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT	1,275	1,268
Operating Earnings	$ 28,083	$ 33,305
Cement [Member] \| Operating Segments [Member] \| Joint Venture [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT	236	243
Operating Earnings	$ 9,251	$ 9,876
Cement [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(4,178)	(4,929)
Concrete and Aggregates [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	40,840	43,919
Operating Earnings	5,484	6,021
Capital Expenditures	2,064	1,412
Depreciation, Depletion and Amortization	2,053	1,914
Identifiable Assets	109,641		104,851
Concrete and Aggregates [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(331)	(413)
Gypsum Wallboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	142,415	126,813
Operating Earnings	50,480	43,821
Capital Expenditures	2,355	5,642
Depreciation, Depletion and Amortization	4,830	4,442
Identifiable Assets	386,094		386,041
Paperboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	45,133	44,413
Operating Earnings	9,994	4,938
Capital Expenditures	1,065	764
Depreciation, Depletion and Amortization	2,109	2,137
Identifiable Assets	120,565		123,819
Paperboard [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(17,347)	(17,357)
Oil and Gas Proppants [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	21,758	18,910
Operating Earnings	(2,691)	(2,026)
Capital Expenditures	27,636	579
Depreciation, Depletion and Amortization	7,139	7,606
Identifiable Assets	420,075		$ 401,421
Other [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	5,942
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	$ 798	$ 369

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