Inventories Stated at Lower of Average Cost or Market (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Inventory [Line Items]
Inventories	$ 190,711	$ 187,096
Raw Materials and Material-in-Progress [Member]
Inventory [Line Items]
Inventories	91,255	82,319
Finished Cement [Member]
Inventory [Line Items]
Inventories	12,965	19,173
Gypsum Wallboard [Member]
Inventory [Line Items]
Inventories	7,400	7,144
Frac Sand [Member]
Inventory [Line Items]
Inventories	376	275
Aggregates [Member]
Inventory [Line Items]
Inventories	10,869	11,815
Paperboard [Member]
Inventory [Line Items]
Inventories	3,936	4,102
Repair Parts and Supplies [Member]
Inventory [Line Items]
Inventories	57,331	56,119
Fuel and Coal [Member]
Inventory [Line Items]
Inventories	$ 6,579	$ 6,149