Stockholders' Equity Stock-Based Compensation Expense By Statement Of Operations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Stock-based employee compensation expense related to employee stock options and employee stock purchases, pre tax	$ 9,347	$ 7,595	$ 2,634
Tax benefit	0	0	0
Stock-based employee compensation expense related to employee stock options and employee stock purchases, net of tax	9,347	7,595	2,634
Cost of service revenue
Stock-based employee compensation expense related to employee stock options and employee stock purchases, pre tax	692	372	211
Cost of product revenue
Stock-based employee compensation expense related to employee stock options and employee stock purchases, pre tax	0	0	0
Research and development
Stock-based employee compensation expense related to employee stock options and employee stock purchases, pre tax	1,495	967	428
Sales and marketing
Stock-based employee compensation expense related to employee stock options and employee stock purchases, pre tax	3,748	2,217	1,363
General and administrative
Stock-based employee compensation expense related to employee stock options and employee stock purchases, pre tax	$ 3,412	$ 4,039	$ 632