Supplementary Balance Sheet Information (Components Of Accounts Payable And Accrued Liabilities) (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Jul. 31, 2018	Apr. 30, 2018
Balance Sheet Related Disclosures [Abstract]
Trade payables	$ 80,218	$ 80,793	$ 58,228
Deferred revenue	297,874	282,103	251,110
Accrued salaries, wages and deferred compensation	37,817	40,034	24,645
Accrued benefits	42,732	33,963	37,776
Deposits	32,090	26,646	24,326
Other liabilities	52,329	40,994	33,773
Total accounts payable and accrued liabilities	$ 543,060	$ 504,533	$ 429,858