Supplementary Balance Sheet Information (Components Of Accounts Payable And Accrued Liabilities) (Details) - USD ($) $ in Thousands	Oct. 31, 2017	Jul. 31, 2017	Oct. 31, 2016
Balance Sheet Related Disclosures [Abstract]
Trade payables	$ 103,540	$ 71,558	$ 90,773
Deferred revenue	407,848	240,096	328,009
Accrued salaries, wages and deferred compensation	19,699	44,869	29,544
Accrued benefits	30,317	32,505	28,564
Deposits	21,017	23,742	18,418
Other liabilities	48,046	54,899	47,615
Total accounts payable and accrued liabilities	$ 630,467	$ 467,669	$ 542,923