Income Taxes Deferred Income Taxes (Details) (USD $)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Current deferred taxes:
Accrued expense	$ 180,000	$ 230,000
Prepaid expenses	(102,000)	(91,000)
Other current	222,000	105,000
Total current deferred taxes	300,000	244,000
Valuation allowance - current	(240,000)	(200,000)
Net current deferred taxes	60,000	44,000
Non-current deferred taxes:
Depreciation and amortization	(2,715,000)	(1,456,000)
Deferred rent	954,000	978,000
Accelerated research and experimentation expenditures	(6,819,000)	(5,400,000)
Stock-based compensation	8,804,000	8,105,000
Net operating and capital loss carryforwards	12,034,000	10,209,000
Federal and state tax credits	4,588,000	3,705,000
Other	56,000	98,000
Total non-current deferred taxes	16,902,000	16,239,000
Valuation allowance	(19,130,000)	(16,998,000)
Net non-current deferred taxes	(2,228,000)	(759,000)
Net deferred taxes	(2,168,000)	(715,000)
Gross deferred tax assets	26,800,000	23,400,000
Gross deferred tax liabilities	(9,600,000)	(6,900,000)
Change in valuation allowance related to deferred tax assets and liabilities	$ 2,200,000	$ 3,100,000	$ 10,100,000