CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning Balance at Dec. 31, 2014	$ 704,322	$ 833	$ (367,121)	$ 779,138	$ (23,488)	$ 314,960
Beginning Balance, shares (in shares) at Dec. 31, 2014		83,288
Beginning Balance, Treasury Stock, shares (in shares) at Dec. 31, 2014			(17,814)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(3,519)					(3,519)
Other comprehensive income (loss), net of tax	(24,414)
Separation of SeaSpine	(167,229)				(1,667)	(165,562)
Other comprehensive income (loss), net of tax and SeaSpine	(22,747)				(22,747)
Treasury Share purchases (in shares)			(16)
Issuance of common stock	219,680	$ 80		219,600
Issuance of common stock, shares (in shares)		8,006
Issuance of common stock through employee stock purchase plan	231			231
Issuance of common stock through employee stock purchase plan (in shares)		8
Issuance of common stock for vesting of share based awards, net of shares withheld for taxes	5,255	$ 4		5,251
Issuance of common stock for vesting of share based awards, net of shares withheld for taxes (in shares)		412
Share-based compensation	15,450			15,450
Ending Balance at Dec. 31, 2015	751,443	$ 917	$ (367,121)	1,019,670	(47,902)	145,879
Ending Balance, shares (in shares) at Dec. 31, 2015		91,714
Ending Balance, Treasury Stock, shares (in shares) at Dec. 31, 2015			(17,830)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	74,564					74,564
Other comprehensive income (loss), net of tax	(9,252)				(9,252)
Treasury shares retirement	0	$ (178)	$ 367,121	(366,943)
Treasury shares retirement (in shares)		(17,830)	(17,830)
Issuance of common stock through employee stock purchase plan	391	$ 1		390
Issuance of common stock through employee stock purchase plan (in shares)		12
Issuance of common stock for vesting of share based awards, net of shares withheld for taxes	5,211	$ 8		5,203
Issuance of common stock for vesting of share based awards, net of shares withheld for taxes (in shares)		824
Settlement of convertible notes		$ 29		(29)
Settlement of convertible notes (in shares)		2,946
Exercise of convertible note hedge			$ (123,051)	123,051
Exercise of convertible note hedge (in shares)			(2,946)
Share-based compensation	17,310			17,310
Ending Balance at Dec. 31, 2016	$ 839,667	$ 777	$ (123,051)	798,652	(57,154)	220,443
Ending Balance, shares (in shares) at Dec. 31, 2016		77,666
Ending Balance, Treasury Stock, shares (in shares) at Dec. 31, 2016	(2,946)		(2,946)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 64,743					64,743
Other comprehensive income (loss), net of tax	33,347				33,347
Issuance of common stock	1	$ 1
Issuance of common stock, shares (in shares)		135
Issuance of common stock through employee stock purchase plan	509	$ 0		509
Issuance of common stock through employee stock purchase plan (in shares)		12
Issuance of common stock for vesting of share based awards, net of shares withheld for taxes	2,137	$ 7	$ 1,407	723
Issuance of common stock for vesting of share based awards, net of shares withheld for taxes (in shares)		653	19
Exercise of warrants (in shares)		2,840
Exercise of warrants		$ 28		(28)
Share-based compensation	21,902			21,902
Ending Balance at Dec. 31, 2017	$ 962,306	$ 813	$ (121,644)	$ 821,758	$ (23,807)	$ 285,186
Ending Balance, shares (in shares) at Dec. 31, 2017		81,306
Ending Balance, Treasury Stock, shares (in shares) at Dec. 31, 2017	(2,912)		(2,927)