Condensed Consolidated Statements of Cash Flows (unaudited) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 8,962,894	$ 5,648,987
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,270,895	2,182,129
Stock-based compensation expense	788,326	633,073
Deferred income taxes	(269,149)	14,036
Provision for doubtful accounts		135,353
Provision for inventory	229,885	164,300
Tax benefit from exercise of stock options	(7,596)	(400,325)
Changes in operating assets and liabilities:
Accounts receivable	1,796,522	(892,265)
Inventories	(2,324,269)	(3,713,817)
Prepaid expenses, other current and long-term assets	703,303	590,614
Long-term deposits and other	16,998	16,997
Accounts payable	878,228	(170,035)
Accrued expenses	(1,270,885)	(920,168)
Deferred revenue	(1,430,484)	(1,433,334)
Income taxes payable	(440,210)	1,679,579
Other long-term liabilities	(271,532)	(335)
Net cash provided by operating activities	9,632,926	3,534,789
Cash flows from investing activities:
Proceeds from sales of assets	246,785
Purchase of property and equipment, net	(109,871)	(1,145,493)
Net cash provided by (used in) investing activities	136,914	(1,145,493)
Cash flows from financing activities:
Principal payments on debt	(800,000)	(800,000)
Proceeds from exercise of stock options	1,127,875	147,033
Tax benefit from exercise of stock options	7,596	400,325
Net cash provided by (used in) financing activities	335,471	(252,642)
Exchange rate impact on cash	(32,329)	(4,268)
Increase in cash and cash equivalents	10,072,982	2,132,386
Cash and cash equivalents at beginning of period	44,067,477	35,777,222
Cash and cash equivalents at end of period	$ 54,140,459	$ 37,909,608