ACQUISITIONS (Asset Acquisition, Narrative) (Details)				3 Months Ended		12 Months Ended
	Jan. 04, 2021 USD ($)	Sep. 09, 2019 USD ($) asset	Jan. 04, 2019 USD ($) asset	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Schedule Of Asset Acquisition [Line Items]
IPR&D expense						$ 0	$ 64,916,000	$ 0
Intangible asset				$ 1,031,591,000		989,436,000	1,031,591,000
Consortium of Focused Orthopedists, LLC | Subsequent Event | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Smith & Nephew USD Limited
Schedule Of Asset Acquisition [Line Items]
Sale of Extremity Orthopedics business, payment for terminating license agreement	$ 41,500,000
Rebound
Schedule Of Asset Acquisition [Line Items]
Upfront payment		$ 67,100,000
Contingent development milestone payments commitment (up to)		$ 35,000,000.0
Number of assets acquired | asset		1
Remaining net assets acquired		$ 7,200,000
Development milestone payment, to be paid				5,000,000.0		20,000,000.0	5,000,000.0
IPR&D expense				$ 5,000,000.0			$ 5,000,000.0
Intangible asset						$ 20,000,000.0
Rebound | Cash and Cash Equivalents
Schedule Of Asset Acquisition [Line Items]
Remaining net assets acquired		2,100,000
Rebound | Deferred Tax Asset
Schedule Of Asset Acquisition [Line Items]
Remaining net assets acquired		4,200,000
Rebound | IPR&D
Schedule Of Asset Acquisition [Line Items]
Upfront payment		$ 59,900,000
ISC
Schedule Of Asset Acquisition [Line Items]
Research and development expense					$ 1,700,000
ISC | Enabling technology license
Schedule Of Asset Acquisition [Line Items]
Number of assets acquired | asset			1
Upfront payment, intangible assets			$ 1,700,000
Option to acquire, period subsequent to first commercial sale			4 years
Maximum future purchase price, if circumstances met (not to exceed)			$ 80,000,000.0