Financial Information Related to Operations by Segment (Detail) $ in Thousands	3 Months Ended
	Jun. 30, 2017 USD ($) T	Jun. 30, 2016 USD ($) T	Mar. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Revenues	$ 366,121	$ 297,504
Net Revenues, including Joint Venture	394,291	322,392
Less: Joint Venture	(28,170)	(24,888)
Operating Earnings	96,692	81,010
Corporate General and Administrative	(9,679)	(9,833)
Earnings Before Interest and Income Taxes	87,013	71,177
Interest Expense, Net	(7,483)	(3,901)
Earnings Before Income Taxes	79,530	67,276
Capital Expenditures	16,160	8,978
Depreciation, Depletion and Amortization	28,947	22,863
Identifiable Assets	2,279,590		$ 2,247,124
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	416,990	340,716
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(22,699)	(18,324)
Other, net [Member]
Segment Reporting Information [Line Items]
Operating Earnings	757	1,075
Capital Expenditures	45
Depreciation, Depletion and Amortization	369	457
Cement [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	$ 182,935	$ 144,792
Cement Sales Volume | T	1,511	1,251
Operating Earnings	$ 43,181	$ 31,600
Capital Expenditures	7,718	5,245
Depreciation, Depletion and Amortization	12,479	$ 8,611
Identifiable Assets	$ 1,263,484		1,234,617
Cement [Member] | Operating Segments [Member] | Joint Venture [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume | T	243	218
Operating Earnings	$ 9,876	$ 7,980
Cement [Member] | Operating Segments [Member] | Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume | T	1,268	1,033
Operating Earnings	$ 33,305	$ 23,620
Cement [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(4,929)	(3,535)
Gypsum Wallboard [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	126,813	113,262
Operating Earnings	43,821	39,336
Capital Expenditures	5,642	1,328
Depreciation, Depletion and Amortization	4,442	4,762
Identifiable Assets	377,562		379,414
Paperboard [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	44,413	42,815
Operating Earnings	4,938	11,227
Capital Expenditures	764	1,304
Depreciation, Depletion and Amortization	2,137	2,100
Identifiable Assets	126,583		124,356
Paperboard [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(17,357)	(14,506)
Oil and Gas Proppants [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	18,910	5,096
Operating Earnings	(2,026)	(5,912)
Capital Expenditures	579	57
Depreciation, Depletion and Amortization	7,606	5,184
Identifiable Assets	373,964		376,306
Concrete and Aggregates [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	43,919	34,751
Operating Earnings	6,021	3,684
Capital Expenditures	1,412	1,044
Depreciation, Depletion and Amortization	1,914	1,749
Identifiable Assets	110,575		110,413
Concrete and Aggregates [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(413)	$ (283)
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	$ 27,422		$ 22,018