Fair Value of Financial Instruments (Details) (USD $)	Jul. 31, 2011	Jul. 31, 2010
Financial assets at fair value
Total financial assets, Fair Value	$ 82,076,000	$ 98,579,000
Financial liabilities at fair value
Total financial liabilities, Fair Value	8,438,000	452,000
Fair Value of Financial Instruments (Textuals)
Carrying Value Of Short Term Borrowings And Long Term Debt	693,673,000	782,036,000
The total fair value of short-term borrowings and long-term debt	850,000,000	850,000,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 1 [Member] | Other assets, net [Member]
Financial assets at fair value
Derivative Assets, Fair Value	0	0
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 2 [Member] | Other assets, net [Member]
Financial assets at fair value
Derivative Assets, Fair Value	7,905,000	6,901,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 3 [Member] | Other assets, net [Member]
Financial assets at fair value
Derivative Assets, Fair Value	0	0
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Other assets, net [Member]
Financial assets at fair value
Derivative Assets, Fair Value	7,905,000	6,901,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Other assets, net [Member]
Financial assets at fair value
Derivative Assets, Fair Value	7,905,000	6,901,000
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 1 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	0	0
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 1 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	0
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 2 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	2,322,000	1,220,000
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 2 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	146,000
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 3 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	0	0
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 3 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	0
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	2,322,000	1,220,000
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	146,000
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	2,322,000	1,220,000
Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	146,000
Precious Metal Collars [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 1 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		0
Precious Metal Collars [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 2 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		151,000
Precious Metal Collars [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 3 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		0
Precious Metal Collars [Member] | Cash Flow Hedging [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		151,000
Precious Metal Collars [Member] | Cash Flow Hedging [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		151,000
Foreign Exchange Forward [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 1 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	0
Foreign Exchange Forward [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 2 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	8,258,000
Foreign Exchange Forward [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 3 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	0
Foreign Exchange Forward [Member] | Cash Flow Hedging [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	8,258,000
Foreign Exchange Forward [Member] | Cash Flow Hedging [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	8,258,000
Foreign Exchange Forward [Member] | Nondesignated [Member] | Fair Value, Inputs, Level 1 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	0	0
Foreign Exchange Forward [Member] | Nondesignated [Member] | Fair Value, Inputs, Level 1 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	0	0
Foreign Exchange Forward [Member] | Nondesignated [Member] | Fair Value, Inputs, Level 2 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	75,000	184,000
Foreign Exchange Forward [Member] | Nondesignated [Member] | Fair Value, Inputs, Level 2 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	34,000	452,000
Foreign Exchange Forward [Member] | Nondesignated [Member] | Fair Value, Inputs, Level 3 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	0	0
Foreign Exchange Forward [Member] | Nondesignated [Member] | Fair Value, Inputs, Level 3 [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	0	0
Foreign Exchange Forward [Member] | Nondesignated [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	75,000	184,000
Foreign Exchange Forward [Member] | Nondesignated [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	34,000	452,000
Foreign Exchange Forward [Member] | Nondesignated [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value	75,000	184,000
Foreign Exchange Forward [Member] | Nondesignated [Member] | Accounts payable and accrued liabilities [Member]
Financial liabilities at fair value
Derivative liabilities, Fair Value	34,000	452,000
Put Option [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 1 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		0
Put Option [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 2 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		856,000
Put Option [Member] | Cash Flow Hedging [Member] | Fair Value, Inputs, Level 3 [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		0
Put Option [Member] | Cash Flow Hedging [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		856,000
Put Option [Member] | Cash Flow Hedging [Member] | Prepaid expenses and other current assets [Member]
Financial assets at fair value
Derivative Assets, Fair Value		856,000
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Other assets, net [Member]
Financial assets at fair value
Financial Assets, Fair Value related to mutual fund	39,564,000	41,318,000
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Other assets, net [Member]
Financial assets at fair value
Financial Assets, Fair Value related to mutual fund	0	0
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Other assets, net [Member]
Financial assets at fair value
Financial Assets, Fair Value related to mutual fund	0	0
Mutual Funds [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Other assets, net [Member]
Financial assets at fair value
Financial Assets, Fair Value related to mutual fund	39,564,000	41,318,000
Mutual Funds [Member] | Other assets, net [Member]
Financial assets at fair value
Financial Assets, Fair Value related to mutual fund	39,564,000	41,318,000
Bank Time Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Short-term Investments [Member]
Financial assets at fair value
Financial Assets, Fair Value	32,210,000	47,949,000
Bank Time Deposits [Member] | Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member]
Financial assets at fair value
Financial Assets, Fair Value	0	0
Bank Time Deposits [Member] | Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member]
Financial assets at fair value
Financial Assets, Fair Value	0	0
Bank Time Deposits [Member] | Carrying (Reported) Amount, Fair Value Disclosure [Member] | Short-term Investments [Member]
Financial assets at fair value
Financial Assets, Fair Value	32,210,000	47,949,000
Bank Time Deposits [Member] | Short-term Investments [Member]
Financial assets at fair value
Financial Assets, Fair Value	32,210,000	47,949,000
Fair Value, Inputs, Level 1 [Member]
Financial assets at fair value
Total financial assets, Fair Value	71,774,000	89,267,000
Financial liabilities at fair value
Total financial liabilities, Fair Value	0	0
Fair Value, Inputs, Level 2 [Member]
Financial assets at fair value
Total financial assets, Fair Value	10,302,000	9,312,000
Financial liabilities at fair value
Total financial liabilities, Fair Value	8,438,000	452,000
Fair Value, Inputs, Level 3 [Member]
Financial assets at fair value
Total financial assets, Fair Value	0	0
Financial liabilities at fair value
Total financial liabilities, Fair Value	0	0
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Financial assets at fair value
Total financial assets, Fair Value	82,076,000	98,579,000
Financial liabilities at fair value
Total financial liabilities, Fair Value	$ 8,438,000	$ 452,000