Statements Of Cash Flows (USD $)	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
OPERATING ACTIVITIES
Net income	$ 3,377,658	$ 3,439,228
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	139,271	113,537
Deferred income taxes	3,282	(6,948)
Changes in operating assets and liabilities:
Accounts receivable	(262,256)	193,257
Inventories	(317,720)	(24,871)
Prepaid expenses and other assets	(39,839)	147,642
Accounts payable and accrued expenses	1,199,601	1,213,150
Net cash provided by operating activities	4,099,997	5,074,995
INVESTING ACTIVITIES
Purchases of fixed assets	(445,186)	(199,371)
Purchases of marketable securities	(6,195,829)	(5,011,799)
Proceeds from maturities and sales of marketable securities	2,490,000	861,397
Net cash used in investing activities	(4,151,015)	(4,349,773)
Increase (decrease) in cash and cash equivalents	(51,018)	725,222
Cash and cash equivalents at beginning of period	1,544,536	952,209
Cash and cash equivalents at end of period	1,493,518	1,677,431
Supplemental disclosures of cash flow information:
Cash (refunded) paid during the period for income taxes	$ 0	$ (2,435)