Financial Information Related to Operations by Segment (Detail) $ in Thousands	3 Months Ended
Jun. 30, 2020 USD ($) kT	Jun. 30, 2019 USD ($) kT	Mar. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Revenue	$ 428,020	$ 370,597
Less: Joint Venture Revenue	(25,300)	(27,505)
Operating Earnings	108,775	84,761
Corporate General and Administrative Expense	(17,789)	(21,254)
Gain on Sale of Businesses	51,973
Other Non-Operating Income (Loss)	(127)	200
Earnings Before Interest and Income Taxes	142,832	63,707
Interest Expense, Net	(14,041)	(8,846)
Earnings before Income Taxes	128,791	54,861
Capital Expenditures	25,991	25,488
Depreciation, Depletion and Amortization	31,937	27,960
Identifiable Assets	3,015,164		$ 2,961,020
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	473,526	419,747
Operating Earnings	60,455	36,121
Operating Segments [Member] \| Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Operating Earnings	52,659	26,689
Operating Segments [Member] \| Joint Venture [Member]
Segment Reporting Information [Line Items]
Operating Earnings	7,796	9,432
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(20,206)	(21,645)
Revenue	(20,206)	(21,645)
Other, net [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	348,505		271,145
Cement [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	$ 261,411	$ 195,313
Cement Sales Volume \| kT	2,085	1,550
Operating Earnings	$ 60,455	$ 36,121
Capital Expenditures	10,348	10,537
Depreciation, Depletion and Amortization	19,243	$ 14,218
Identifiable Assets	$ 1,999,175		1,980,306
Cement [Member] \| Operating Segments [Member] \| Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT	1,866	1,318
Cement [Member] \| Operating Segments [Member] \| Joint Venture [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume \| kT	219	232
Cement [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	$ (6,031)	$ (4,253)
Concrete and Aggregates [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	44,190	39,778
Operating Earnings	5,418	4,434
Capital Expenditures	1,261	595
Depreciation, Depletion and Amortization	2,721	2,191
Identifiable Assets	99,298		136,041
Concrete and Aggregates [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(106)	(377)
Gypsum Wallboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	130,150	126,724
Operating Earnings	41,325	37,932
Capital Expenditures	6,512	1,931
Depreciation, Depletion and Amortization	5,200	4,952
Identifiable Assets	372,628		375,946
Paperboard [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	36,744	42,700
Operating Earnings	2,895	9,944
Capital Expenditures	7,870	12,360
Depreciation, Depletion and Amortization	3,352	2,163
Identifiable Assets	187,511		183,288
Paperboard [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(14,069)	(17,015)
Oil and Gas Proppants [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue	1,031	15,232
Operating Earnings	(1,318)	(3,670)
Capital Expenditures		65
Depreciation, Depletion and Amortization	121	3,839
Identifiable Assets	8,047		$ 14,294
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	$ 1,300	$ 597

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