Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 6,717	$ 4,489	$ 3,877
Additions Charged to Costs and Expenses	5,715	3,780	3,465
Deductions	(3,951)	(1,552)	(2,853)
Balance at End of Year	8,481	6,717	4,489
Allowance for Inventory Obsolescence [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	264	237	210
Additions Charged to Costs and Expenses	43	27	27
Balance at End of Year	$ 307	$ 264	$ 237