Condensed Consolidated Income Statements (unaudited) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2018	[1]	Sep. 30, 2017	Sep. 30, 2018	[1]	Sep. 30, 2017
Revenue:
Total Revenues	$ 8,168,081		$ 6,516,108	$ 23,108,264		$ 20,742,243
Costs and expenses:
Research and development	162,625		356,847	569,648		949,359
General and administrative	2,232,077		2,175,501	6,345,662		6,916,501
Total Cost and Expenses	2,394,702		2,532,348	6,915,310		7,865,860
Operating income	5,773,379		3,983,760	16,192,954		12,876,383
Other income:
Interest income	359,637		193,462	851,334		436,210
Other income	0		14,667	96,663		40,651
Total other income	359,637		208,129	947,997		476,861
Income before income tax expense	6,133,016		4,191,889	17,140,951		13,353,244
Provision for income tax expense	(1,089,966)		(1,477,057)	(3,271,366)		(4,669,569)
Net income	$ 5,043,050		$ 2,714,832	$ 13,869,585		$ 8,683,675
Basic net income per share (in dollars per share)	$ 0.69		$ 0.38	$ 1.92		$ 1.21
Diluted net income per share (in dollars per share)	$ 0.69		$ 0.37	$ 1.89		$ 1.19
Shares used in computation of basic net income per share (in shares)	7,281,388		7,164,934	7,230,106		7,166,470
Shares used in computation of diluted net income per share (in shares)	7,356,885		7,314,609	7,327,029		7,325,602
Royalties [Member]
Revenue:
Total Revenues	$ 8,168,081		$ 6,511,700	$ 23,068,585		$ 20,729,017
Licensing Revenues [Member]
Revenue:
Total Revenues	$ 0		$ 4,408	$ 39,679		$ 13,226

[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. 3-Summary of Significant Accounting Policies for additional discussion.