Stock Plans (Assumptions Used In Black-Scholes Model) (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2012 Percent	Sep. 30, 2011 Percent	Sep. 30, 2012 Percent	Sep. 30, 2011 Percent
Option Grants and Stock Purchase Rights
Expected volatility	68.00%	76.00%	68.00%	76.00%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	0.71%	0.31%	0.71%	0.33%
Weighted average expected option term, in years	5.40	3.00	5.30	3.00
Weighted average fair value of options granted, per share	$ 3.38	$ 2.27	$ 3.33	$ 2.25
Employee Stock Purchase Plan Rights
Expected volatility	34.00%	68.00%	34.00%	68.00%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	0.16%	0.10%	0.16%	0.10%
Weighted average expected option term, in years	0.75	0.75	0.75	0.75
Weighted average fair value of options granted, per share	$ 1.45	$ 1.49	$ 1.45	$ 1.49