Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities:
Consolidated net income	$ 25,965	$ 41,437
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	46,329	32,630
Loss on repurchases of convertible notes	17,444
Amortization of non-cash interest	10,943	8,749
Stock-based compensation	12,357	13,493
Reserves on current assets	6,751	4,083
Other non-cash adjustments	8,387	10,669
Deferred income taxes	14,691	19,996
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable	(8,615)	637
Inventory	(12,019)	(15,181)
Prepaid expenses and other current assets	728	1,182
Accounts payable and accrued liabilities	14,273	6,841
Accrued royalties	111	(47,112)
Accrued payroll and related expenses	(4,356)	(8,370)
Litigation liability	(43,310)	4,795
Income taxes	10,534	(38,666)
Net cash provided by operating activities	100,213	35,183
Investing activities:
Acquisition of Ellipse Technologies, net of cash acquired	(380,080)
Other acquisitions and investments	(8,079)	(1,357)
Purchases of intangible assets	(5,918)	(28,589)
Purchases of property and equipment	(52,566)	(47,976)
Purchases of marketable securities	(128,956)	(129,549)
Proceeds from sales of marketable securities	339,320	164,147
Sales of restricted investments		33,809
Purchases of restricted investments		(62,625)
Net cash used in investing activities	(236,279)	(72,140)
Financing activities:
Incremental tax benefits related to stock-based compensation awards		9,928
Proceeds from the issuance of common stock	6,150	8,360
Payment of contingent consideration		(514)
Purchase of treasury stock	(22,549)	(43,937)
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	(1,545)	(87)
Net cash provided by (used in) financing activities	206,061	(26,250)
Effect of exchange rate changes on cash	748	(543)
Increase (decrease) in cash and cash equivalents	70,743	(63,750)
Cash and cash equivalents at beginning of period	192,339	142,387
Cash and cash equivalents at end of period	$ 263,082	$ 78,637