Quarterly report pursuant to Section 13 or 15(d)

Goodwill and intangible assets (Detail)

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Goodwill and intangible assets (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Oct. 31, 2012
Jul. 31, 2012
Oct. 31, 2012
Clinical Labs [Member]
Jul. 31, 2012
Clinical Labs [Member]
Oct. 31, 2012
Intangible Assets, Amortization Period [Member]
Goodwill $ 7,452 $ 7,452 $ 7,452 $ 7,452  
Finite-Lived Intangible Asset, Useful Life         7 years