Basis of Presentation - Carrying Amounts and Fair Values of Financial Instruments (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Assets
Money market funds	$ 194,428,575	$ 85,500,745
Marketable securities – certificates of deposit	1,087,197	1,066,103
Marketable securities – equity securities	67,283	60,999
Total	195,583,055	86,627,847
Level 1
Assets
Money market funds	194,428,575	85,500,745
Marketable securities – certificates of deposit	1,087,197	1,066,103
Marketable securities – equity securities	67,283	60,999
Total	195,583,055	86,627,847
Level 2
Assets
Money market funds	0	0
Marketable securities – certificates of deposit	0	0
Marketable securities – equity securities	0	0
Total	0	0
Level 3
Assets
Money market funds	0	0
Marketable securities – certificates of deposit	0	0
Marketable securities – equity securities	0	0
Total	$ 0	$ 0