Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Current Assets -
Cash and Cash Equivalents	$ 21,676	$ 6,561	$ 164,665	$ 5,391
Accounts and Notes Receivable	143,662	136,313
Inventories	239,628	252,846
Prepaid and Other Current Assets	20,378	4,904
Total Current Assets	425,344	400,624
Property, Plant and Equipment -	2,547,430	2,439,438
Less: Accumulated Depreciation	(972,706)	(892,601)
Property, Plant and Equipment, net	1,574,724	1,546,837
Notes Receivable	296	815
Investment in Joint Venture	55,337	48,620
Goodwill and Intangible Assets, net	240,145	235,505
Other Assets	12,197	14,723
Total Assets	2,308,043	2,247,124
Current Liabilities -
Accounts Payable	73,203	92,193
Accrued Liabilities	101,432	55,379
Income Tax Payable		733
Current Portion of Long-term Debt		81,214
Total Current Liabilities	174,635	229,519
Long-term Debt	565,755	605,253
Other Long-term Liabilities	35,112	42,878
Deferred Income Taxes	116,352	166,024
Total Liabilities	891,854	1,043,674
Total Stockholders’ Equity	1,416,189	1,203,450
Liabilities and Stockholders' Equity, Total	2,308,043	2,247,124
Eliminations [Member]
Current Assets -
Income Tax Receivable		(33,196)
Total Current Assets		(33,196)
Investments in Subsidiaries and Receivables from Affiliates	(9,071,980)	(8,378,598)
Total Assets	(9,071,980)	(8,411,794)
Current Liabilities -
Income Tax Payable		(33,196)
Total Current Liabilities		(33,196)
Payables to Affiliates	(6,476,414)	(6,078,019)
Total Liabilities	(6,476,414)	(6,111,215)
Total Stockholders’ Equity	(2,595,566)	(2,300,579)
Liabilities and Stockholders' Equity, Total	(9,071,980)	(8,411,794)
Parent [Member]
Current Assets -
Cash and Cash Equivalents	18,078	5,184	162,792	3,507
Accounts and Notes Receivable	394	422
Income Tax Receivable		33,196
Prepaid and Other Current Assets	15,208	484
Total Current Assets	33,680	39,286
Property, Plant and Equipment -	3,148	2,914
Less: Accumulated Depreciation	(1,029)	(937)
Property, Plant and Equipment, net	2,119	1,977
Investment in Joint Venture	65	51
Investments in Subsidiaries and Receivables from Affiliates	5,544,333	5,126,289
Other Assets	5,482	5,687
Total Assets	5,585,679	5,173,290
Current Liabilities -
Accounts Payable	5,813	6,687
Accrued Liabilities	62,485	21,043
Income Tax Payable		733
Current Portion of Long-term Debt		81,214
Total Current Liabilities	68,298	109,677
Long-term Debt	565,755	605,253
Other Long-term Liabilities	140	189
Payables to Affiliates	3,527,647	3,252,309
Deferred Income Taxes	7,650	2,412
Total Liabilities	4,169,490	3,969,840
Total Stockholders’ Equity	1,416,189	1,203,450
Liabilities and Stockholders' Equity, Total	5,585,679	5,173,290
Guarantor Subsidiaries [Member]
Current Assets -
Cash and Cash Equivalents	3,598	1,377	$ 1,873	$ 1,884
Accounts and Notes Receivable	143,268	135,891
Inventories	239,628	252,846
Prepaid and Other Current Assets	5,170	4,420
Total Current Assets	391,664	394,534
Property, Plant and Equipment -	2,544,282	2,436,524
Less: Accumulated Depreciation	(971,677)	(891,664)
Property, Plant and Equipment, net	1,572,605	1,544,860
Notes Receivable	296	815
Investment in Joint Venture	55,272	48,569
Investments in Subsidiaries and Receivables from Affiliates	3,527,647	3,252,309
Goodwill and Intangible Assets, net	240,145	235,505
Other Assets	6,715	9,036
Total Assets	5,794,344	5,485,628
Current Liabilities -
Accounts Payable	67,390	85,506
Accrued Liabilities	38,947	34,336
Income Tax Payable		33,196
Total Current Liabilities	106,337	153,038
Other Long-term Liabilities	34,972	42,689
Payables to Affiliates	2,948,767	2,825,710
Deferred Income Taxes	108,702	163,612
Total Liabilities	3,198,778	3,185,049
Total Stockholders’ Equity	2,595,566	2,300,579
Liabilities and Stockholders' Equity, Total	$ 5,794,344	$ 5,485,628

Investments in subsidiaries and receivables from affiliates.

No definition available.

Name:	exp_InvestmentsInSubsidiariesAndReceivablesFromAffiliates
Namespace Prefix:	exp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate of amounts due from customers or clients, within one year of the balance sheet date (or one operating cycle, if longer), for goods or services that have been delivered or sold in the normal course of business and an amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date within one year of the balance sheet, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection and net of any write-downs taken for collection uncertainty on the part of the holder, respectively.