Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Apr. 30, 2018	Apr. 30, 2018	Jan. 31, 2018	Apr. 30, 2018
Income Taxes [Line Items]
Effective tax rate	21.00%	29.73%	35.00%	33.33%
Deferred income tax expense				$ 680,000
Tax Cuts and Jobs Act, transition tax for accumulated unrepatriated foreign earnings, provisional income tax expense				649,000
Tax Cuts and Jobs Act, transition tax for accumulated unrepatriated foreign earnings, provisional income tax liability	$ 546,000	$ 546,000		$ 546,000
Tax Cuts and Jobs Act, transition tax for accumulated unrepatriated foreign earnings, payment period				8 years
State tax credit carry forward	221,000	221,000		$ 221,000
State tax credit carry forwards, expiration beginning date				2018
Gross net operating losses	1,240,000	1,240,000		$ 1,240,000
Gross net operating losses subject to expiration	$ 624,000	$ 624,000		624,000
Valuation allowance				$ 175,000
Minimum [Member]
Income Taxes [Line Items]
Gross net operating losses expiration year				2020
Federal, state and local tax returns period				3 years
Foreign subsidiaries tax returns period				3 years
Maximum [Member]
Income Taxes [Line Items]
Gross net operating losses expiration year				2023
Federal, state and local tax returns period				4 years
Foreign subsidiaries tax returns period				7 years