Financial Information Related to Operations by Segment (Detail) $ in Thousands	3 Months Ended
Jun. 30, 2019 USD ($) kT	Jun. 30, 2018 USD ($) kT	Mar. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Revenue	$ 370,597	$ 393,756
Less: Joint Venture Revenue	(27,505)	(27,264)
Operating Earnings	84,761	100,885
Corporate General and Administrative Expense	(21,254)	(8,003)
Litigation Settlements and Losses		(1,800)
Other Non-Operating Income	200	571
Earnings Before Interest and Income Taxes	63,707	91,653
Interest Expense, Net	(8,846)	(6,632)
Earnings before Income Taxes	54,861	85,021
Capital Expenditures	25,488	53,073
Depreciation, Depletion and Amortization	27,960	29,850
Identifiable Assets	2,269,078		$ 2,169,163
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	419,747	442,876
Operating Earnings	36,121	37,334
Operating Segments [Member] \| Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Operating Earnings	26,689	28,083
Operating Segments [Member] \| Joint Venture [Member]
Segment Reporting Information [Line Items]
Operating Earnings	9,432	9,251
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(21,645)	(21,856)
Other [Member]
Segment Reporting Information [Line Items]
Capital Expenditures		340
Identifiable Assets	44,482		37,434
Cement [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	$ 195,313	$ 186,788
Cement Sales Volume \| kT	1,550	1,511
Operating Earnings	$ 36,121	$ 37,334
Capital Expenditures	10,537	19,613
Depreciation, Depletion and Amortization	14,218	$ 12,921
Identifiable Assets	$ 1,331,042		1,289,468
Cement [Member] \| Operating Segments [Member] \| Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT	1,318	1,275
Cement [Member] \| Operating Segments [Member] \| Joint Venture [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT	232	236
Cement [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	$ (4,253)	$ (4,178)
Concrete and Aggregates [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	39,778	40,840
Operating Earnings	4,434	5,484
Capital Expenditures	595	2,064
Depreciation, Depletion and Amortization	2,191	2,053
Identifiable Assets	107,127		95,084
Concrete and Aggregates [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(377)	(331)
Gypsum Wallboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	126,724	142,415
Operating Earnings	37,932	50,480
Capital Expenditures	1,931	2,355
Depreciation, Depletion and Amortization	4,952	4,830
Identifiable Assets	372,961		372,206
Paperboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	42,700	45,133
Operating Earnings	9,944	9,994
Capital Expenditures	12,360	1,065
Depreciation, Depletion and Amortization	2,163	2,109
Identifiable Assets	148,148		138,614
Paperboard [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(17,015)	(17,347)
Oil and Gas Proppants [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	15,232	27,700
Operating Earnings	(3,670)	(2,407)
Capital Expenditures	65	27,636
Depreciation, Depletion and Amortization	3,839	7,595
Identifiable Assets	265,318		$ 236,357
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	$ 597	$ 342

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