Balance Sheets (USD $)	Mar. 31, 2015	Mar. 31, 2014
ASSETS
Cash and cash equivalents	$ 9,437,262	$ 1,262,300
Marketable securities, short term	20,099,288us-gaap_MarketableSecuritiesCurrent	12,360,091us-gaap_MarketableSecuritiesCurrent
Accounts receivable, net of allowance for uncollectible accounts of $15,000	2,963,974us-gaap_AccountsReceivableNetCurrent	2,331,574us-gaap_AccountsReceivableNetCurrent
Inventories	3,742,492us-gaap_InventoryNet	3,207,333us-gaap_InventoryNet
Deferred tax assets	102,052	237,387
Prepaid expenses and other assets	574,913	816,276
Total current assets	36,919,981us-gaap_AssetsCurrent	20,214,961us-gaap_AssetsCurrent
Fixed assets
Machinery and equipment	8,604,926us-gaap_MachineryAndEquipmentGross	8,536,010us-gaap_MachineryAndEquipmentGross
Leasehold improvements	1,524,298us-gaap_LeaseholdImprovementsGross	1,499,454us-gaap_LeaseholdImprovementsGross
Gross fixed assets	10,129,224us-gaap_PropertyPlantAndEquipmentGross	10,035,464us-gaap_PropertyPlantAndEquipmentGross
Less accumulated depreciation	7,873,816	7,030,692
Net fixed assets	2,255,408us-gaap_PropertyPlantAndEquipmentNet	3,004,772us-gaap_PropertyPlantAndEquipmentNet
Marketable securities, long term	70,913,807us-gaap_MarketableSecuritiesNoncurrent	82,022,310us-gaap_MarketableSecuritiesNoncurrent
Total assets	110,089,196us-gaap_Assets	105,242,043us-gaap_Assets
LIABILITIES AND SHAREHOLDERS' EQUITY
Accounts payable	358,818us-gaap_AccountsPayableCurrent	374,127us-gaap_AccountsPayableCurrent
Accrued payroll and other	1,127,136	808,675
Total current liabilities	1,485,954us-gaap_LiabilitiesCurrent	1,182,802us-gaap_LiabilitiesCurrent
Long-term deferred tax liabilities	275,708	354,600
Shareholders' equity
Common stock, $0.01 par value, 6,000,000 shares authorized; 4,857,953 issued and outstanding as of March 31, 2015 and 4,851,043 issued and outstanding as of March 31, 2014	48,580us-gaap_CommonStockValue	48,510us-gaap_CommonStockValue
Additional paid-in capital	20,850,762	20,464,883
Accumulated other comprehensive income	746,447	877,857
Retained earnings	86,681,745	82,313,391
Total shareholders' equity	108,327,534us-gaap_StockholdersEquity	103,704,641us-gaap_StockholdersEquity
Total liabilities and shareholders' equity	$ 110,089,196	$ 105,242,043

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Subparagraph a

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682