Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended			3 Months Ended				1 Months Ended
	Mar. 31, 2014 Patient	Mar. 02, 2011	Feb. 18, 2011 Minimum [Member]	Mar. 31, 2014 Hologic [Member]	Mar. 31, 2013 Hologic [Member]	Mar. 31, 2014 Zeiss [Member]	Mar. 31, 2013 Zeiss [Member]	Feb. 28, 2010 CADx Medical Systems Inc. [Member]	Jul. 31, 2007 CADx Medical Systems Inc. [Member]
Loss Contingencies [Line Items]
Tax re-assessment received									$ 6,800,000
Reduced tax re-assessment received								703,000
Minimum annual royalty payment	250,000
Fair value of patent license	100,000
Patent license, Estimated Amortizable Life	6 years
Minimum royalty obligations	587,000
Interest expense royalty obligation				24,000	30,000	28,000	45,000
June 2015	500,000
June 2017	500,000
Litigation and settlement obligation, Total	1,000,000
Royalty obligation non-current	754,000
Purchase obligations to suppliers for future product deliverables	1,500,000
Unlimited damages sought by plaintiffs			25,000
Aggregate amount of damages sought		$ 14,500,000
Number of patients treated using the Axxent Flexishield Mini as part of a clinical trial	29