Pension and Other Postretirement Benefits Assumptions (Details)	6 Months Ended
	Jan. 31, 2016	Jan. 31, 2015
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Discount rate for net periodic benefit cost	4.22%	4.28%
Rate of increase in compensation levels	3.50%	3.50%
Long-term expected rate of return on assets	7.50%	7.50%
Postretirement Health Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Discount rate for net periodic benefit cost	3.51%	3.87%
Rate of increase in compensation levels	0.00%	0.00%
Long-term expected rate of return on assets	0.00%	0.00%