Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income	$ 8,455,431	$ 6,959,083
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization	1,215,814	647,071
Stock-based compensation expense	100,428	72,305
Deferred tax expense	(2,747,864)	441,211
Changes in operating assets and liabilities:
Accounts receivable	(1,298,832)	(1,273,079)
Income tax receivable	916,843	(521,121)
Prepaid expenses and other current assets	(170,591)	(136,152)
Patent costs	(23,341)	(24,204)
Accounts payable and accrued expenses	380,858	107,372
Income taxes payable	279,333	0
Deferred revenue	7,667,163	(37,034)
Net cash provided by operating activities	14,775,242	6,235,452
Cash flows from investing activities:
Maturity of marketable investments	32,548,040	11,043,544
Purchases of marketable investments	(47,568,734)	(24,422,334)
Net cash used in investing activities	(15,020,694)	(13,378,790)
Cash flows from financing activities:
Proceeds from stock option exercises	529,300	2,813,984
Payments for repurchase of common stock	(898,025)	(1,182,068)
Excess tax benefits from share-based payment arrangements	224,047	3,188,682
Net cash (used in) provided by financing activities	(144,678)	4,820,598
Decrease in cash and cash equivalents	(390,130)	(2,322,740)
Cash and cash equivalents at beginning of year	5,137,875	9,810,816
Cash and cash equivalents at end of period	4,747,745	7,488,076
Cash paid during the period for:
Interest	0	0
Taxes	$ 5,825,000	$ 546,000