Patents and other intangible assets (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of Patents and Other Intangible Assets

	December 31,
(US$ in thousands)	2012			2011
Cost
Patents	$	37,695		$	37,683
Trademarks—definite lived		657			545
		38,352			38,228
Accumulated amortization
Patents		(31,045	)		(29,611	)
Trademarks—definite lived		(427	)		(381	)
		(31,472	)		(29,992	)
Patents and other intangible assets, net	$	6,880		$	8,236