Statements of Comprehensive Income - USD ($)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 13,912,672	$ 12,948,869	$ 12,292,315
Unrealized loss from marketable securities, net of tax	(877,337)	(489,657)	(295,088)
Comprehensive income	$ 13,035,335	$ 12,459,212	$ 11,997,227