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Fair Value Measurements (Details) (USD $)
In Thousands, unless otherwise specified
Apr. 30, 2015
Jul. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis    
Cash equivalents $ 4,026odc_CashEquivalentsFairValueDisclosure $ 5,728odc_CashEquivalentsFairValueDisclosure
Marketable equity securities 0odc_MarketableEquitySecuritiesNoncurrentFairValueDisclosure 117odc_MarketableEquitySecuritiesNoncurrentFairValueDisclosure
Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis    
Cash equivalents 4,026odc_CashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 5,728odc_CashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Marketable equity securities $ 0odc_MarketableEquitySecuritiesNoncurrentFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 $ 117odc_MarketableEquitySecuritiesNoncurrentFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member