Fair Value - Quantitative Information about Inputs and Valuation Methodologies Used for Fair Value Measurements of Contingent Consideration Classified in Level 3 (Detail) - Senhance Surgical Robotic System Acquisition [Member] - Significant Unobservable Inputs (Level 3) [Member] - Contingent Consideration [Member]	9 Months Ended
	Sep. 30, 2017
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Probability of occurrence	100.00%
Minimum [Member]
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Milestone dates	2017
Discount rate	7.50%
Maximum [Member]
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Milestone dates	2020
Discount rate	11.75%