Fair Value of Financial Instruments - Financial Assets and Liabilities Carried at Fair Value (Detail) (USD $) | Apr. 30, 2014 | Apr. 30, 2013 |
In Thousands, unless otherwise specified |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Total financial assets, Fair Value | $79,290 | | $74,580 | |
Total financial liabilities, Fair Value | 1,380 | | 4,127 | |
Other assets, net [Member] | Marketable securities [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 53,393 | [1] | 50,067 | [1] |
Short-term Investments [Member] | Bank Time Deposits [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 21,901 | [2] | 125 | [2] |
Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 197 | [3] | 205 | [3] |
Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 3,799 | [3] | 24,183 | [3] |
Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 1,077 | [4] | 4,047 | [4] |
Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 303 | [4] | 80 | [4] |
Carrying Value [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Total financial assets, Fair Value | 79,290 | | 74,580 | |
Total financial liabilities, Fair Value | 1,380 | | 4,127 | |
Carrying Value [Member] | Other assets, net [Member] | Marketable securities [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 53,393 | [1] | 50,067 | [1] |
Carrying Value [Member] | Short-term Investments [Member] | Bank Time Deposits [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 21,901 | [2] | 125 | [2] |
Carrying Value [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 197 | [3] | 205 | [3] |
Carrying Value [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 3,799 | [3] | 24,183 | [3] |
Carrying Value [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 1,077 | [4] | 4,047 | [4] |
Carrying Value [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 303 | [4] | 80 | [4] |
Level 1 [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Total financial assets, Fair Value | 75,294 | | 50,192 | |
Total financial liabilities, Fair Value | 0 | | 0 | |
Level 1 [Member] | Other assets, net [Member] | Marketable securities [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 53,393 | [1] | 50,067 | [1] |
Level 1 [Member] | Short-term Investments [Member] | Bank Time Deposits [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 21,901 | [2] | 125 | [2] |
Level 1 [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 0 | [3] | 0 | [3] |
Level 1 [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 0 | [3] | 0 | [3] |
Level 1 [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 0 | [4] | 0 | [4] |
Level 1 [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 0 | [4] | 0 | [4] |
Level 2 [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Total financial assets, Fair Value | 3,996 | | 24,388 | |
Total financial liabilities, Fair Value | 1,380 | | 4,127 | |
Level 2 [Member] | Other assets, net [Member] | Marketable securities [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 0 | [1] | 0 | [1] |
Level 2 [Member] | Short-term Investments [Member] | Bank Time Deposits [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 0 | [2] | 0 | [2] |
Level 2 [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 197 | [3] | 205 | [3] |
Level 2 [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 3,799 | [3] | 24,183 | [3] |
Level 2 [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 1,077 | [4] | 4,047 | [4] |
Level 2 [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 303 | [4] | 80 | [4] |
Level 3 [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Total financial assets, Fair Value | 0 | | 0 | |
Total financial liabilities, Fair Value | 0 | | 0 | |
Level 3 [Member] | Other assets, net [Member] | Marketable securities [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 0 | [1] | 0 | [1] |
Level 3 [Member] | Short-term Investments [Member] | Bank Time Deposits [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Financial Assets, Fair Value | 0 | [2] | 0 | [2] |
Level 3 [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 0 | [3] | 0 | [3] |
Level 3 [Member] | Prepaid expenses and other current assets [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Assets, Fair Value | 0 | [3] | 0 | [3] |
Level 3 [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Precious Metal Forward Contracts [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | 0 | [4] | 0 | [4] |
Level 3 [Member] | Accounts payable and accrued liabilities [Member] | Cash Flow Hedging [Member] | Foreign Exchange Contract [Member] | ' | | ' | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | | ' | |
Derivative Liabilities, Fair Value | $0 | [4] | $0 | [4] |
|
[1] | Included within Other assets, net. |
[2] | Included within Short-term investments. |
[3] | Included within Prepaid expenses and other current assets. |
[4] | Included within Accounts payable and accrued liabilities. |