Schedule of Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Accounts Payable And Accrued Liabilities Current [Abstract]
Payroll and Incentive Compensation	$ 14,956	$ 12,855
Benefits	10,139	10,158
Interest	4,813	4,813
Property Taxes	5,008	2,801
Power and Fuel	1,836	2,132
Sales and Use Tax	868	658
Legal	1,341	1,831
Acquisition and Litigation	2,103
Other	6,781	6,272
Accrued expenses, total	$ 47,845	$ 41,520