Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Consolidated net income (loss)	$ 35,426	$ 65,290	$ (17,496)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	102,713	65,915	65,837
Deferred income tax expense (benefit)	26,265	34,757	(23,231)
Loss on repurchases of convertible notes	19,085
Amortization of non-cash interest	22,721	17,851	16,490
Stock-based compensation	26,924	26,203	33,687
Impairment of intangible assets			10,708
Reserves on current assets	11,408	9,454	1,856
Other non-cash adjustments	16,928	17,581	13,191
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable	(33,250)	(9,463)	(18,465)
Inventory	(22,636)	(25,984)	(21,343)
Prepaid expenses and other current assets	(5,665)	1,239	(5,183)
Accounts payable and accrued liabilities	11,854	7,742	5,855
Accrued royalties	471	(46,092)	12,410
Accrued payroll and related expenses	8,849	(192)	7,179
Litigation liability	(88,450)	(36,270)	30,000
Income taxes	23,652	(39,304)	4,053
Net cash provided by operating activities	156,295	88,727	115,548
Investing activities:
Acquisition of Ellipse Technologies, net of cash acquired	(380,080)
Other acquisitions and investments	(108,591)	(1,357)	(500)
Purchases of intangible assets	(5,918)	(32,020)
Proceeds from sales of property and equipment		40	241
Purchases of property and equipment	(88,372)	(75,772)	(58,424)
Purchases of marketable securities	(128,956)	(427,945)	(217,158)
Proceeds from sales of marketable securities	407,032	411,471	174,816
Proceeds from sales of restricted investments		180,694
Purchases of restricted investments		(62,625)	(3,800)
Net cash used in investing activities	(304,885)	(7,514)	(104,825)
Financing activities:
Incremental tax benefits related to stock-based compensation awards		15,185	11,896
Proceeds from the issuance of common stock	9,492	12,106	23,354
Payment of contingent consideration	(422)	(514)	(498)
Purchase of treasury stock	(24,734)	(56,929)	(3,782)
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	(439,519)
Proceeds from revolving line of credit	50,000
Repayments on revolving line of credit	(50,000)
Other financing activities	(1,834)	(192)	(693)
Net cash provided by (used in) financing activities	110,823	(30,344)	30,277
Effect of exchange rate changes on cash	(929)	(917)	(1,438)
(Decrease) increase in cash and cash equivalents	(38,696)	49,952	39,562
Cash and cash equivalents at beginning of year	192,339	142,387	102,825
Cash and cash equivalents at end of year	153,643	192,339	142,387
Supplemental disclosure of non-cash transactions:
Intangible asset purchase			27,389
Issuance of common stock in connection with royalty milestone achievement	5,761		3,161
Supplemental cash flow information:
Interest paid	13,249	11,069	11,069
Income taxes (refunded) paid	$ (20,499)	$ 36,303	$ 13,640