Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 3,344,753	$ 2,829,124
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization	545,067	414,744
Stock-based compensation expense	33,476	33,476
Deferred tax expense	97,508	(2,819,285)
Changes in operating assets and liabilities:
Accounts receivable	(1,117,501)	(1,239,234)
Income tax receivable	212,174	(12,000)
Prepaid expenses and other current assets	40,709	(83,320)
Patent costs	0	(5,414)
Accounts payable and accrued expenses	422,793	26,739
Deferred revenue	(259,713)	8,237,655
Net cash provided by operating activities	3,319,266	7,382,485
Cash flows from investing activities:
Maturity of marketable investments	18,217,000	12,233,583
Purchases of marketable investments	(17,304,251)	(15,169,104)
Net cash provided by (used in) investing activities	912,749	(2,935,521)
Cash flows from financing activities:
Proceeds from stock option exercises	258,250	177,250
Payments for repurchase of common stock	(221,821)	(398,976)
Excess tax benefits from share-based payment arrangements	0	151,380
Net cash provided by (used in) financing activities	36,429	(70,346)
Increase in cash and cash equivalents	4,268,444	4,376,618
Cash and cash equivalents at beginning of year	4,763,364	5,137,875
Cash and cash equivalents at end of period	9,031,808	9,514,493
Cash paid during the period for:
Interest	0	0
Taxes	$ 1,460,000	$ 4,080,000