Schedule of Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Inventory [Line Items]
Inventories	$ 241,599	$ 275,194
Raw Materials and Material-in-Progress [Member]
Inventory [Line Items]
Inventories	101,904	125,828
Finished Cement [Member]
Inventory [Line Items]
Inventories	22,062	27,826
Aggregates [Member]
Inventory [Line Items]
Inventories	7,228	7,351
Gypsum Wallboard [Member]
Inventory [Line Items]
Inventories	5,587	7,124
Paperboard [Member]
Inventory [Line Items]
Inventories	11,364	15,660
Frac Sand [Member]
Inventory [Line Items]
Inventories	2,913	2,557
Repair Parts and Supplies [Member]
Inventory [Line Items]
Inventories	80,712	80,676
Fuel and Coal [Member]
Inventory [Line Items]
Inventories	$ 9,829	$ 8,172