Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 31, 2018	Apr. 30, 2018
Summary Of Significant Accounting Policies [Line Items]
Net sales	$ 121,078,000	$ 111,708,000	$ 111,547,000	$ 108,709,000	$ 116,896,000	$ 105,247,000	$ 108,942,000	$ 102,738,000	$ 453,042,000	$ 433,823,000	$ 409,788,000
Freezing amount in cash resulted from court pending legal action issued	2,600,000								2,600,000			$ 2,600,000
Spinal Kinetics [Member]
Summary Of Significant Accounting Policies [Line Items]
In-process research and development costs	$ 26,800,000								26,800,000				$ 26,800,000
Musculoskeletal Transplant Foundation ("MTF") [Member]
Summary Of Significant Accounting Policies [Line Items]
Expenditures for other research and development									0	900,000	1,300,000
Customers and Distributors Based in Europe [Member]
Summary Of Significant Accounting Policies [Line Items]
Net sales									69,000,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Transactional foreign currency gains and (losses), including those generated from intercompany operations									$ (3,300,000)	1,900,000	(100,000)
General and administrative [Member]
Summary Of Significant Accounting Policies [Line Items]
Increase (decrease) of general and administrative expense										$ (2,500,000)	$ 2,000,000.0