Goodwill and intangible assets (Details 1) (USD $) In Thousands	Jul. 31, 2011	Oct. 31, 2010
Summary of intangible assets subject to amortization
Carrying Amount	$ 77,104	$ 63,157
Accumulated Amortization	27,623	23,329
Net Book Value	49,481	39,828
Patent costs [Member]
Summary of intangible assets subject to amortization
Carrying Amount	22,212	20,641
Accumulated Amortization	8,609	6,961
Net Book Value	13,603	13,680
Customer relationships [Member]
Summary of intangible assets subject to amortization
Carrying Amount	39,115	30,630
Accumulated Amortization	10,972	8,273
Net Book Value	28,143	22,357
Non-compete agreements [Member]
Summary of intangible assets subject to amortization
Carrying Amount	4,695	5,982
Accumulated Amortization	3,623	4,857
Net Book Value	1,072	1,125
Core/developed technology [Member]
Summary of intangible assets subject to amortization
Carrying Amount	2,788	2,788
Accumulated Amortization	2,299	2,123
Net Book Value	489	665
Trade name [Member]
Summary of intangible assets subject to amortization
Carrying Amount	6,850	1,684
Accumulated Amortization	1,345	479
Net Book Value	5,505	1,205
Other [Member]
Summary of intangible assets subject to amortization
Carrying Amount	1,444	1,432
Accumulated Amortization	775	636
Net Book Value	$ 669	$ 796