Income Taxes Deferred Income Taxes (Details) (USD $)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Current deferred taxes:
Accrued expense	$ 282,000	$ 225,000
Prepaid expenses	(76,000)	(68,000)
Other current	9,000	142,000
Total current deferred taxes	215,000	299,000
Valuation allowance - current	(251,000)	(251,000)
Net current deferred taxes	(36,000)	48,000
Non-current deferred taxes:
Depreciation and amortization	(800,000)	69,000
Deferred rent	989,000	589,000
Accelerated research and experimentation expenditures	(4,042,000)	(3,517,000)
Stock-based compensation	6,442,000	5,167,000
Net operating and capital loss carryforwards	9,510,000	710,000
Federal and state tax credits	1,076,000	618,000
Other	142,000	124,000
Total non-current deferred taxes	13,317,000	3,760,000
Valuation allowance	(13,891,000)	(3,839,000)
Net non-current deferred taxes	(574,000)	(79,000)
Net deferred taxes	(610,000)	(31,000)
Gross deferred tax assets	18,500,000	7,600,000
Gross deferred tax liabilities	4,900,000	3,600,000
Change in valuation allowance related to deferred tax assets and liabilities	10,100,000	3,900,000	150,000
Tax benefits (charges) recorded in other comprehensive income (loss) related to the unrealized (gains) losses on available for sale securities	$ 0	$ (53,000)