CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING ACTIVITIES:
Net income (loss)	$ 64,743	$ 74,564	$ (3,519)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Loss from discontinued operations, net of tax	0	0	10,370
Depreciation and amortization	88,945	72,665	58,863
Non-cash impairment charges	3,290	0	380
Deferred income tax benefit	(67,304)	(6,474)	(351)
Non-cash valuation allowance	0	0	37,210
Share-based compensation	21,550	17,310	15,450
Amortization of debt issuance costs	2,722	2,529	2,264
Non-cash interest expense	0	8,074	7,911
Realized loss on sale of sale of short-term investment	2,287	0	0
Loss on disposal of property and equipment	6,989	1,765	481
Gain on divestiture of business	(2,645)	0	0
Change in fair value of contingent consideration and others	(4,710)	(13)	(177)
Gain on bargain purchase	0	0	(1,111)
Payment of accreted interest	0	(42,786)	(384)
Changes in assets and liabilities, net of business acquisitions:
Accounts receivable	(89,698)	(17,518)	(16,231)
Inventories	99	(9,576)	(3,759)
Prepaid expenses and other current assets	(33,808)	14,912	(233)
Other non-current assets	(914)	(475)	610
Accounts payable, accrued expenses and other current liabilities	95,321	(414)	8,208
Deferred revenue	3,874	1,251	136
Other non-current liabilities	23,803	591	945
Net cash provided by operating activities of continuing operations	114,544	116,405	117,063
Net cash used in operating activities of discontinued operations	0	0	(12,209)
Net cash provided by operating activities	114,544	116,405	104,854
INVESTING ACTIVITIES:
Change in restricted cash	0	4,165	(4,087)
Proceeds from sale of short-term investments	16,951	0	0
Proceeds from note receivable	483	0	0
Cash used in business acquisitions, net of cash acquired	(1,241,946)	225	(328,888)
Purchases of property and equipment	(43,503)	(47,328)	(33,413)
Proceeds from sales of property and equipment	293	316	1,438
Proceeds from divestiture of business	46,387	0	0
Net cash used in investing activities of continuing operations	(1,221,335)	(42,622)	(364,950)
Net cash used in investing activities of discontinued operations	0	0	(7,060)
Net cash used in investing activities	(1,221,335)	(42,622)	(372,010)
FINANCING ACTIVITIES:
Borrowings under senior credit facility	1,307,000	680,000	545,000
Repayments under senior credit facility	(117,000)	(511,250)	(465,625)
Net cash paid for contingent consideration	(4,661)	0	0
Proceeds from the issuance of common stock, net of issuance costs	0	0	219,669
Distribution to SeaSpine	0	0	(47,013)
Payment of liability component of convertible notes	0	(184,313)	(2,519)
Payment of capital lease obligation	0	(653)	(709)
Debt issuance costs	(19,043)	(4,530)	(1,426)
Proceeds from exercised stock options	9,774	10,481	7,345
Cash taxes paid in net equity settlement	(7,123)	(4,851)	(6,580)
Net cash provided by (used in) financing activities	1,168,947	(15,116)	248,142
Effect of exchange rate changes on cash and cash equivalents	10,724	(4,744)	(4,848)
Net increase (decrease) in cash and cash equivalents	72,880	53,923	(23,862)
Cash and cash equivalents at beginning of period	102,055	48,132	71,994
Cash and cash equivalents at end of period	$ 174,935	$ 102,055	$ 48,132