Pension and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Interest cost	$ 266	$ 583	$ 534	$ 583
Expected return on plan assets	(646)	(1,444)	(1,293)	(1,444)
Amortization of Other actuarial loss	35	265	72	435
Net periodic benefit cost	(345)	(596)	(687)	(426)
Postretirement Health Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	28	34	61	69
Interest cost	13	12	29	25
Amortization of Other actuarial loss	0	2	0	2
Amortization of Prior service costs	(2)	(2)	(3)	(3)
Net periodic benefit cost	$ 39	$ 46	$ 87	$ 93