BACKGROUND AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Revenues	$ 196,215	$ 169,236	$ 573,701	$ 517,031
Cash and cash equivalents	166,090	145,295	166,090	145,295	$ 139,647	$ 118,817
Restricted Cash	100		100		100
Capital Expenditures Incurred but Not yet Paid			6,000	7,900
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 166,190	$ 145,295	166,190	145,295	$ 139,747	$ 118,817
Payments to Acquire Investments			277,446	382,347
Proceeds from Sale of Available-for-sale Securities			$ 46,474	$ 85,234
Diluted	$ 0.38	$ 0.35	$ 1.08	$ 1.18
Musculoskeletal Solutions [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenues	$ 182,324	$ 163,068	$ 540,620	$ 484,400
Enabling Technologies [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenues	$ 13,891	$ 6,168	$ 33,081	$ 32,631