Schedule of Property, Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,962,215	$ 1,660,975
Accumulated Depreciation	(740,396)	(676,924)
Property, Plant and Equipment, net	1,221,819	984,051
Land And Quarries [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	345,991	171,987
Plants [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,378,497	1,357,594
Buildings Machinery And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	151,627	111,263
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 86,100	$ 20,131