Business Segments - Financial Information Related to Operations by Segment (Detail) $ in Thousands		12 Months Ended
		Mar. 31, 2025 USD ($) kt	Mar. 31, 2024 USD ($) kt	Mar. 31, 2023 USD ($) kt
Segment Reporting Information [Line Items]
Revenue		$ 2,260,508	$ 2,259,297	$ 2,148,069
Corporate General and Administrative Expense		(73,942)	(59,795)	(53,630)
Other Nonoperating Income (Loss)		6,420	3,087	2,654
Interest Expense, net		(40,526)	(42,257)	(35,171)
Earnings Before Income Taxes		591,485	617,937	588,593
Capital Expenditures		195,281	120,305	110,143
Freight and Delivery		269,685
Depreciation, Depletion and Amortization		158,902	149,832	138,554
Segment Assets		3,264,588	2,947,019	2,781,002
External Customers [Member]
Segment Reporting Information [Line Items]
Revenue		2,260,508	2,259,297	2,148,069
Intersegment [Member]
Segment Reporting Information [Line Items]
Revenue		139,770	130,654	125,750
Joint Venture [Member]
Segment Reporting Information [Line Items]
Revenue		110,943	112,736	113,518
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue		2,511,221	2,502,687	2,387,337
Freight and Delivery			278,071	302,537
Parts, Supplies, and Services (Includes Maintenance)		302,269	282,162	229,972
Energy		196,329	217,670	224,772
Raw Materials		468,167	461,725	467,623
Labor and Fixed Costs		282,862	268,803	236,032
Depreciation, Depletion and Amortization	[1]	155,653	146,715	135,742
Purchased Cement		77,059	86,219	47,454
Other Segment Items		59,664	44,420	68,465
Segment Profit		699,533	716,902	674,740
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue		(139,770)	(130,654)	(125,750)
Consolidation, Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue		(110,943)	(112,736)	(113,518)
Cement [Member]
Segment Reporting Information [Line Items]
Freight and Delivery		90,996
Cement [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Revenue		1,053,620	1,077,918	927,637
Cement [Member] | Intersegment [Member]
Segment Reporting Information [Line Items]
Revenue		36,799	35,363	32,915
Cement [Member] | Joint Venture [Member]
Segment Reporting Information [Line Items]
Revenue		110,943	112,736	113,518
Cement [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue		$ 1,201,362	$ 1,226,017	$ 1,074,070
Cement Sales Volume | kt		6,912	7,289	7,133
Operating Earnings		$ 319,456	$ 338,349	$ 278,762
Capital Expenditures		139,965	65,442	39,049
Freight and Delivery			94,031	97,126
Parts, Supplies, and Services (Includes Maintenance)		231,530	217,393	183,706
Energy		140,754	154,925	149,445
Raw Materials		84,669	87,154	75,617
Labor and Fixed Costs		162,741	155,118	141,719
Depreciation, Depletion and Amortization	[1]	91,817	89,138	81,643
Purchased Cement		77,059	86,219	47,454
Other Segment Items		2,340	3,690	18,598
Segment Profit		319,456	338,349	278,762
Segment Assets		$ 2,172,459	$ 2,042,499	$ 1,905,227
Cement [Member] | Operating Segments [Member] | Wholly-Owned [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume | kt		6,237	6,610	6,399
Operating Earnings		$ 293,060	$ 306,768	$ 243,288
Cement [Member] | Operating Segments [Member] | Joint Venture [Member]
Segment Reporting Information [Line Items]
Cement Sales Volume | kt		675	679	734
Operating Earnings		$ 26,396	$ 31,581	$ 35,474
Concrete and Aggregates [Member]
Segment Reporting Information [Line Items]
Freight and Delivery		32,593
Concrete and Aggregates [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Revenue		237,723	240,012	239,516
Concrete and Aggregates [Member] | Intersegment [Member]
Segment Reporting Information [Line Items]
Revenue		13,913	12,940	0
Concrete and Aggregates [Member] | Joint Venture [Member]
Segment Reporting Information [Line Items]
Revenue			0	0
Concrete and Aggregates [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue		251,636	252,952	239,516
Capital Expenditures		20,571	15,103	35,503
Freight and Delivery			33,976	36,115
Parts, Supplies, and Services (Includes Maintenance)		39,109	31,246	17,724
Energy		7,562	7,641	5,236
Raw Materials		109,587	112,447	112,269
Labor and Fixed Costs		36,722	31,014	19,511
Depreciation, Depletion and Amortization	[1]	23,247	19,728	17,413
Purchased Cement				0
Other Segment Items		11,581	4,499	12,989
Segment Profit		(8,765)	12,401	18,259
Segment Assets		408,792	225,485	234,767
Gypsum Wallboard [Member]
Segment Reporting Information [Line Items]
Freight and Delivery		146,000
Gypsum Wallboard [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Revenue		846,499	839,530	872,471
Gypsum Wallboard [Member] | Intersegment [Member]
Segment Reporting Information [Line Items]
Revenue		0	0	0
Gypsum Wallboard [Member] | Joint Venture [Member]
Segment Reporting Information [Line Items]
Revenue			0	0
Gypsum Wallboard [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue		846,499	839,530	872,471
Capital Expenditures		15,843	29,127	31,063
Freight and Delivery			149,441	160,536
Parts, Supplies, and Services (Includes Maintenance)		19,032	22,337	17,933
Energy		33,978	37,984	50,177
Raw Materials		179,142	178,340	184,677
Labor and Fixed Costs		61,968	59,796	54,041
Depreciation, Depletion and Amortization	[1]	25,807	23,038	21,744
Purchased Cement
Other Segment Items		29,808	34,058	30,864
Segment Profit		350,764	334,536	352,499
Segment Assets		429,268	432,122	421,425
Recycled Paperboard [Member]
Segment Reporting Information [Line Items]
Freight and Delivery		96
Recycled Paperboard [Member] | External Customers [Member]
Segment Reporting Information [Line Items]
Revenue		122,666	101,837	108,445
Recycled Paperboard [Member] | Intersegment [Member]
Segment Reporting Information [Line Items]
Revenue		89,058	82,351	92,835
Recycled Paperboard [Member] | Joint Venture [Member]
Segment Reporting Information [Line Items]
Revenue			0	0
Recycled Paperboard [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue		211,724	184,188	201,280
Capital Expenditures		15,193	10,085	2,898
Freight and Delivery			623	8,760
Parts, Supplies, and Services (Includes Maintenance)		12,598	11,186	10,609
Energy		14,035	17,120	19,914
Raw Materials		94,769	83,784	95,060
Labor and Fixed Costs		21,431	22,875	20,761
Depreciation, Depletion and Amortization	[1]	14,782	14,811	14,942
Purchased Cement
Other Segment Items		15,935	2,173	6,014
Segment Profit		38,078	31,616	25,220
Segment Assets		166,673	170,832	163,797
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Capital Expenditures		3,709	548	1,630
Segment Assets		$ 87,396	$ 76,081	$ 55,786

[1] Depreciation, Depletion, and Amortization for corporate assets was $3,249 million, $3,117 million, and $2,812 million, in fiscal 2025, 2024, and 2023, respectively. These amounts are included in Corporate General and Administrative Expense.