Cash, Cash Equivalents And Marketable Securities (Narrative) (Details) (USD $)	12 Months Ended		12 Months Ended			0 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Minimum [Member] M	Mar. 31, 2012 Maximum [Member] M	Mar. 31, 2012 Auction Rate Securities [Member]	Jun. 01, 2012 Forecast [Member] Auction Rate Securities [Member]
Cash, Cash Equivalents and Marketable Securities [Line Items]
Long-term marketable securities	$ 16,644,000	$ 27,880,000			$ 1,500,000
Long-term marketable securities, par value					19,300,000
Long-term marketable securities, estimated market value					19,100,000
Auction rate securities redemption at par by issuers					4,500,000	17,600,000
Short-term marketable securities, current					17,600,000
Period used as basis for computation of weighted average assumption period for reclassification of security to liquidity (months)			51	55
Cumulative temporary decline in value of marketable securities	2,100,000
Reduction in the valuation reserve reflecting redemptions at par	190,000
Reduction in the valuation reserve reflecting redemptions at par, net of tax	117,000
Cumulative temporary decline in value of marketable securities, net of tax	$ 1,300,000