Investments - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Marketable Securities [Abstract]
Impairment of investments	$ 0	$ 0	$ 0	$ 0
Ownership interest in four limited partnerships, fair value	3,320,010		3,320,010		$ 4,051,399
Ownership interest in four limited partnerships, cost	2,800,000		2,800,000		$ 3,547,687
Realized gain on sale of investment in limited partnership	$ 36,714	$ 0	$ 36,714	$ 0