Condensed Consolidated Statements of Equity (Unaudited) - USD ($)		Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Mar. 31, 2017		2,042,789
Balance at Mar. 31, 2017		$ 510,696	$ 4,205,536	$ 18,461,347	$ (212,047)	$ (803,138)	$ 22,162,394
Net income (loss)*	[1]			1,390,090		(317)	1,389,773
Net change from marketable securities, net of tax					(379,480)		(379,480)
Foreign currency translation gain					210,328	23,038	233,366
Redeemable non-controlling interest			(33,550)				(33,550)
Unrealized gain on interest rate swaps, net of tax
Balance (in shares) at Sep. 30, 2017		2,042,789
Balance at Sep. 30, 2017		$ 510,696	4,171,986	19,851,437	(381,199)	(780,417)	23,372,503
Balance (in shares) at Mar. 31, 2018		2,043,607
Balance at Mar. 31, 2018		$ 510,901	4,171,869	20,695,981	(260,900)	(874,767)	24,243,084
Net income (loss)*	[1]			1,507,509		(88,449)	1,419,060
Foreign currency translation gain					54,758	25,116	79,874
Adoption of ASU 2016-01 | Accounting Standards Update 2016-01 [Member]				(106,341)	106,341
Exercise of stock options (in shares)		1,682
Exercise of stock options		$ 421	17,341				17,762
Repurchase of common stock (in shares)		(675)
Repurchase of common stock		$ (170)	(1,377)	(21,212)			(22,759)
Unrealized gain on interest rate swaps, net of tax					29,124		29,124
Balance (in shares) at Sep. 30, 2018		2,044,614
Balance at Sep. 30, 2018		$ 511,152	$ 4,187,833	$ 22,075,937	$ (70,677)	$ (938,100)	$ 25,766,145

[1] Excludes amount attributable to redeemable non-controlling interest in Contrail Aviation.