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

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration