Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended				6 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income	$ 3,822,062	$ 3,607,419	$ 4,282,610	$ 3,945,049	$ 7,429,481	$ 8,227,659
Unrealized gain from marketable securities, net of tax	178,716	570,063	51,237	(107,027)	748,779	(55,790)
Comprehensive income	$ 4,000,778	$ 4,177,482	$ 4,333,847	$ 3,838,022	$ 8,178,260	$ 8,171,869