Schedule II Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Allowance for Doubtful Accounts, Current
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 230	$ 274	$ 158
Additions	200	181	262
Deductions	294	225	146
Balance at End of Period	136	230	274
Valuation Allowance of Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	118,279	120,721	117,047
Net Change	(330)	(2,442)	3,674
Balance at End of Period	$ 117,949	$ 118,279	$ 120,721