Supplementary Balance Sheet Information (Components Of Accounts Payable And Accrued Liabilities) (Details) - USD ($) $ in Thousands	Apr. 30, 2016	Jul. 31, 2015	Apr. 30, 2015
Balance Sheet Related Disclosures [Abstract]
Trade payables	$ 47,144	$ 62,099	$ 52,371
Deferred revenue	164,927	145,949	115,300
Accrued salaries, wages and deferred compensation	34,403	33,461	38,594
Accrued benefits	29,625	24,436	26,459
Deposits	21,641	19,336	18,199
Other accruals	40,349	46,018	42,133
Total accounts payable and accrued liabilities	$ 338,089	$ 331,299	$ 293,056