Employee Benefit Plans - Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Net periodic postretirement benefit gain included the following components:
Service cost	$ 0	$ 9	$ 210
Interest cost	89	114	222
Amortization of prior service credit	0	(1,035)	(1,169)
Amortization of net actuarial gain	(544)	(646)	(804)
Curtailment gain	0	0	(4,296)
Periodic postretirement benefit gain	$ (455)	$ (1,558)	$ (5,837)