| Goodwill and intangible assets - Additional Information (Detail) (USD $) | 12 Months Ended | ||
|---|---|---|---|
| Jun. 30, 2011 | Jun. 30, 2010 | Jun. 30, 2009 | |
| Cost of Sales | |||
| Finite-Lived Intangible Assets [Line Items] | |||
| Amortization expense of intangible assets | $ 890,000 | $ 435,000 | $ 435,000 | 
| Selling, General and Administrative Expense | |||
| Finite-Lived Intangible Assets [Line Items] | |||
| Amortization expense of intangible assets | $ 574,000 | $ 525,000 | $ 525,000 | 
| X | ||||||||||
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- Definition Aggregate amount of intangible asset amortization recognized as expense during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. 
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