Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating activities:
Consolidated net (loss) income	$ (9,343)	$ 31,397
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	21,224	16,051
Loss on repurchases of convertible notes	17,444
Amortization of non-cash interest	5,112	4,331
Stock-based compensation	4,492	7,611
Reserves on current assets	4,162	633
Other non-cash adjustments	3,491	6,172
Deferred income taxes	1,794	11,015
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable	6,939	5,931
Inventory	(9,449)	(11,367)
Prepaid expenses and other current assets	1,303	444
Accounts payable and accrued liabilities	10,040	17,428
Accrued royalties	(19)	(47,459)
Accrued payroll and related expenses	(9,219)	(10,163)
Litigation liability		7,730
Income taxes	9,421	(13,731)
Net cash provided by operating activities	57,392	26,023
Investing activities:
Acquisition of Ellipse Technologies, net of cash acquired	(380,674)
Other acquisitions and investments	(8,079)	(1,357)
Purchases of intangible assets	(1,027)	(27,389)
Purchases of property and equipment	(18,279)	(30,694)
Purchases of marketable securities	(36,096)	(71,129)
Proceeds from sales of marketable securities	253,435	105,794
Purchases of restricted investments		(32,616)
Net cash used in investing activities	(190,720)	(57,391)
Financing activities:
Incremental tax benefits related to stock-based compensation awards		8,092
Proceeds from the issuance of common stock	444	1,403
Payment of contingent consideration		(514)
Purchase of treasury stock	(12,599)	(30,944)
Proceeds from issuance of convertible debt, net of issuance costs	634,140
Proceeds from sale of warrants	44,850
Purchase of convertible note hedge	(111,150)
Repurchases of convertible notes	(343,835)
Proceeds from revolving line of credit	50,000
Repayments on revolving line of credit	(50,000)
Other financing activities	(1,442)	(45)
Net cash provided by (used in) financing activities	210,408	(22,008)
Effect of exchange rate changes on cash	686	(517)
Increase (decrease) in cash and cash equivalents	77,766	(53,893)
Cash and cash equivalents at beginning of period	192,339	142,387
Cash and cash equivalents at end of period	$ 270,105	$ 88,494