Employees' Retirement Plan (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Retirement Benefits [Abstract]
Pension contributions	$ 109,915	$ 146,183	$ 219,983	$ 247,586
Employer contributions	$ 16,875	$ 14,807	$ 30,573	$ 31,820
Minimum contribution rate			9.10%