Goodwill - Schedule of Net Carrying Amount of Goodwill (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Goodwill [Line Items]
Goodwill, Beginning balance	$ 53,565
Goodwill, Ending balance	72,401
Spinal Kinetics [Member]
Goodwill [Line Items]
Goodwill, Acquisition	18,836
Goodwill, Ending balance	18,836
Bone Growth Therapies [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	42,678
Goodwill, Ending balance	42,678
Spinal Implants [Member]
Goodwill [Line Items]
Goodwill, Ending balance	18,836
Spinal Implants [Member] | Spinal Kinetics [Member]
Goodwill [Line Items]
Goodwill, Acquisition	18,836
Goodwill, Ending balance	18,800
Biologics [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	10,887
Goodwill, Ending balance	$ 10,887