Condensed Consolidated Income Statements (unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2018	[1]	Mar. 31, 2017
Revenue:
Total Revenues	$ 7,089,409		$ 7,690,619
Costs and expenses:
Research and development	195,227		254,781
General and administrative	2,069,633		2,425,717
Total costs and expenses	2,264,860		2,680,498
Operating income	4,824,549		5,010,121
Other income:
Interest income	217,951		101,753
Other income	14,678		2,562
Total other income	232,629		104,315
Income before income tax expense	5,057,178		5,114,436
Provision for income tax expense	(1,078,574)		(1,769,683)
Net income	$ 3,978,604		$ 3,344,753
Basic net income per share (in dollars per share)	$ 0.55		$ 0.47
Diluted net income per share (in dollars per share)	$ 0.54		$ 0.46
Shares used in computation of basic net income per share (in shares)	7,192,900		7,164,248
Shares used in computation of diluted net income per share (in shares)	7,303,336		7,332,736
Royalties [Member]
Revenue:
Total Revenues	$ 7,085,000		$ 7,686,210
Licensing Revenues [Member]
Revenue:
Total Revenues	$ 4,409		$ 4,409

[1] As of January 1, 2018, the Company adopted the requirements of ASC 606 using the modified retrospective adoption method, and as a result, there is a lack of comparability of certain amounts to the prior periods presented. See Note 2 for additional discussion.