Change in Carrying Value of Goodwill (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Goodwill [Roll Forward]
Balance as of December 31, 2012		$ 99,236		$ 99,236
Goodwill from ICA acquisition				3,509
Impairment of goodwill	0	(40,700)	(24,665)	(40,693)	(24,665)
Adjustments 1				(307)
Balance as of September 30, 2013	61,745			61,745
Scanners and CAD/CAM Services
Goodwill [Roll Forward]
Balance as of December 31, 2012		40,693		40,693
Goodwill from ICA acquisition				0
Impairment of goodwill				(40,693)
Adjustments 1				0
Balance as of September 30, 2013	0			0
Clear Aligner [Member]
Goodwill [Roll Forward]
Balance as of December 31, 2012		58,543		58,543
Goodwill from ICA acquisition				3,509
Impairment of goodwill				0
Adjustments 1				(307)
Balance as of September 30, 2013	$ 61,745			$ 61,745