Subsequent Events - Additional Information (Detail) - Subsequent Event [Member] - Spinal Kinetics [Member] |
Apr. 30, 2018
USD ($)
|
|---|---|
| Subsequent Event [Line Items] | |
| Business acquisition date | Apr. 30, 2018 |
| Purchase price paid at closing | $ 45,000,000 |
| Milestone achievement period | 5 years |
| Maximum [Member] | |
| Subsequent Event [Line Items] | |
| Milestone payments | $ 60,000,000 |