Description of Business and Summary of Significant Accounting Policies (Details)	3 Months Ended
	Jun. 30, 2012
Minimum
Warranty
Warranty period	1 year
Minimum | Property and equipment
Property and Equipment
Useful life	3 years
Maximum
Significant accounting policies
Expected period for unbilled amounts to be billed and collected	12 months
Expected period for unearned amounts to be earned	12 months
Cash and Cash Equivalents
Initial maturities of cash and cash equivalents	90 days
Warranty
Warranty period	3 years
Maximum | Property and equipment
Property and Equipment
Useful life	8 years