Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 24,469,808	$ 20,053,269
Adjustments to reconcile net income to net cash provided in operating activities:
Amortization	314,158	2,432,941
Stock-based compensation expense	861,610	263,431
Deferred tax expense	175,084	90,176
Extinguishment of accrued liabilities	0	(78,138)
Non-cash lease expense	3,385	0
Changes in operating assets and liabilities:
Accounts receivable	(2,547,232)	(4,308,855)
Income tax payable	356,969	(763,740)
Prepaid expenses and other current assets	(319,706)	(23,246)
Patent costs	(226,409)	(121,199)
Accounts payable and accrued expenses	(802,518)	325,577
Deferred revenue	0	(139,680)
Net cash provided by operating activities	22,285,149	17,730,536
Cash flows from investing activities:
Maturities of marketable securities	93,068,962	75,170,817
Purchases of marketable securities	(125,102,544)	(86,629,358)
Net cash used in investing activities	(32,033,582)	(11,458,541)
Cash flows from financing activities:
Proceeds from stock option exercises	2,191,816	2,570,830
Repurchases of common stock	(620,652)	(3,000,183)
Net cash provided by (used in) financing activities	1,571,164	(429,353)
(Decrease) increase in cash and cash equivalents	(8,177,269)	5,842,642
Cash and cash equivalents at beginning of year	13,176,452	7,333,810
Cash and cash equivalents at end of year	4,999,183	13,176,452
Supplemental disclosures of cash flow information:
Recognition of right of use asset and related lease obligations	242,877	0
Cash paid during the year for:
Interest	0	0
Taxes	$ 5,292,362	$ 5,417,572