Condensed Consolidated Income Statements (unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues:
Total Revenues	$ 8,129,141	$ 7,089,409
Costs and expenses:
Research and development	149,536	195,227
General and administrative	2,907,160	2,069,633
Total Costs and Expenses	3,056,696	2,264,860
Operating income	5,072,445	4,824,549
Other income:
Interest income	449,425	217,951
Other income	0	14,678
Total other income	449,425	232,629
Income before income tax expense	5,521,870	5,057,178
Provision for income tax expense	(1,105,275)	(1,078,574)
Net income	$ 4,416,595	$ 3,978,604
Basic net income per share (in dollars per share)	$ 0.61	$ 0.55
Diluted net income per share (in dollars per share)	$ 0.60	$ 0.54
Shares used in computation of basic net income per share (in shares)	7,276,885	7,192,900
Shares used in computation of diluted net income per share (in shares)	7,338,128	7,303,336
Royalties [Member]
Revenues:
Total Revenues	$ 8,129,141	$ 7,085,000
Licensing Revenues [Member]
Revenues:
Total Revenues	$ 0	$ 4,409