Acquisitions - Summary of Unaudited Pro forma Results (Detail) - Spinal Kinetics [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Net sales	$ 113,499	$ 111,708	$ 338,461	$ 336,882
Net income (loss)	$ (40,498)	$ (923)	$ (40,148)	$ 5,276