Fair Value - Quantitative Information about Inputs and Valuation Methodologies Used for Fair Value Measurements Classified in Level 3 (Detail) - USD ($) $ in Thousands		9 Months Ended
	Sep. 21, 2015	Sep. 30, 2015
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration		$ 24,300
Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration		24,300
ALF-X Surgical Robotic System Acquisition [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration	$ 24,300	$ 24,300
ALF-X Surgical Robotic System Acquisition [Member] | Fair Value, Inputs, Level 3 [Member] | Contingent Consideration [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Probability of occurrence		100.00%
ALF-X Surgical Robotic System Acquisition [Member] | Fair Value, Inputs, Level 3 [Member] | Contingent Consideration [Member] | Minimum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Milestone dates		2016
Discount rate		7.50%
ALF-X Surgical Robotic System Acquisition [Member] | Fair Value, Inputs, Level 3 [Member] | Contingent Consideration [Member] | Maximum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Milestone dates		2017
Discount rate		9.00%
ALF-X Surgical Robotic System Acquisition [Member] | Fair Value, Inputs, Level 3 [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Contingent consideration		$ 24,300