Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 8,337,399	$ 7,496,423
Cost of sales	7,344,465	6,035,269
Gross profit	992,934	1,461,154
Selling, general and administrative expenses	1,009,544	878,820
Operating (loss) income	(16,610)	582,334
Other income:
Interest income	52,399	31,224
Other	23,671	10,172
Total other income	76,070	41,396
Income before provision for income taxes	59,460	623,730
(Benefit) provision for income taxes	(2,211)	180,966
Net income	61,671	442,764
Other comprehensive income, net of tax:
Unrealized gain (loss) on investment securities	1,347	(281)
Total comprehensive income	$ 63,018	$ 442,483
Net income per share:
Basic	$ 0.03	$ 0.19
Diluted	$ 0.03	$ 0.19
Weighted average number of shares outstanding:
Basic	2,359,493	2,326,364
Diluted	2,382,072	2,332,234
Dividends per share:	$ 1.25	$ 0.25