Nuvasive (NUVA) 10-Q 31 Jul 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 29, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	NUVASIVE INC
Entity Central Index Key	1,142,596
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	NUVA
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		51,422,448

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 70,078	$ 72,803
Restricted cash and investments		3,901
Accounts receivable, net of allowances of $16,782 and $13,026, respectively	199,907	200,220
Inventory, net	259,819	247,138
Prepaid income taxes	18,187	17,209
Prepaid expenses and other current assets	23,588	18,792
Total current assets	571,579	560,063
Property and equipment, net	231,733	215,326
Intangible assets, net	276,318	280,774
Goodwill	560,751	536,926
Deferred tax assets	4,955	6,440
Restricted cash and investments	2,394	1,494
Other assets	24,607	39,117
Total assets	1,672,337	1,640,140
Current liabilities:
Accounts payable and accrued liabilities	89,534	75,767
Contingent consideration liabilities	12,214	18,952
Accrued payroll and related expenses	51,128	55,618
Litigation liabilities	10,300	8,150
Short-term borrowings	37,000
Income tax liabilities	3,825	2,908
Total current liabilities	204,001	161,395
Long-term senior convertible notes	592,581	582,920
Deferred and income tax liabilities, non-current	9,525	18,870
Other long-term liabilities	85,067	77,539
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized, none outstanding
Common stock, $0.001 par value; 120,000,000 shares authorized at June 30, 2018 and December 31, 2017, 56,511,851 and 56,164,060 issued and outstanding at June 30, 2018 and December 31, 2017, respectively	61	60
Additional paid-in capital	1,371,436	1,363,549
Accumulated other comprehensive loss	(8,875)	(6,933)
(Accumulated deficit) retained earnings	(10,839)	4,762
Treasury stock at cost; 5,095,290 shares and 5,001,886 shares at June 30, 2018 and December 31, 2017, respectively	(570,620)	(565,867)
Total NuVasive, Inc. stockholders’ equity	781,163	795,571
Non-controlling interest		3,845
Total equity	781,163	799,416
Total liabilities and equity	$ 1,672,337	$ 1,640,140

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Accounts receivable, allowances	$ 16,782	$ 13,026
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	56,511,851	56,164,060
Common stock, shares outstanding	56,511,851	56,164,060
Treasury stock at cost, shares	5,095,290	5,001,886

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue
Product revenue	$ 252,687	$ 237,824	$ 486,202	$ 462,779
Service revenue	28,877	21,575	55,884	45,633
Total revenue	281,564	259,399	542,086	508,412
Cost of revenue (excluding below amortization of intangible assets)
Cost of products sold	58,202	50,535	113,393	96,436
Cost of services	18,854	15,651	37,477	31,193
Total cost of revenue	77,056	66,186	150,870	127,629
Gross profit	204,508	193,213	391,216	380,783
Operating expenses:
Sales, marketing and administrative	145,658	138,967	292,424	279,335
Research and development	14,856	12,572	29,347	24,986
Amortization of intangible assets	12,628	11,349	25,053	23,410
Litigation liability (gain) loss	(1,195)		27,800
Business transition costs	3,998	1,369	6,251	1,424
Total operating expenses	175,945	164,257	380,875	329,155
Interest and other expense, net:
Interest income	116	139	250	276
Interest expense	(9,956)	(10,083)	(19,423)	(19,882)
Other expense, net	(2,379)	(501)	(12,082)	(243)
Total interest and other expense, net	(12,219)	(10,445)	(31,255)	(19,849)
Income (loss) before income taxes	16,344	18,511	(20,914)	31,779
Income tax (expense) benefit	(4,813)	(6,776)	5,313	(8,061)
Consolidated net income (loss)	11,531	11,735	(15,601)	23,718
Add back net loss attributable to non-controlling interest		(432)		(875)
Net income (loss) attributable to NuVasive, Inc.	$ 11,531	$ 12,167	$ (15,601)	$ 24,593
Net income (loss) per share attributable to NuVasive, Inc.:
Basic	$ 0.22	$ 0.24	$ (0.30)	$ 0.48
Diluted	$ 0.22	$ 0.21	$ (0.30)	$ 0.42
Weighted average shares outstanding:
Basic	51,356	51,082	51,292	50,825
Diluted	51,956	58,330	51,292	58,059

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net income (loss)	$ 11,531	$ 11,735	$ (15,601)	$ 23,718
Other comprehensive (loss) income:
Unrealized gain (loss) on marketable securities, net of tax		1		(1)
Translation adjustments, net of tax	(4,522)	642	(1,943)	2,501
Other comprehensive (loss) income	(4,522)	643	(1,943)	2,500
Total consolidated comprehensive income (loss)	7,009	12,378	(17,544)	26,218
Net loss attributable to non-controlling interest		(432)		(875)
Comprehensive income (loss) attributable to NuVasive, Inc.	$ 7,009	$ 12,810	$ (17,544)	$ 27,093

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Consolidated net (loss) income	$ (15,601)	$ 23,718
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	64,151	58,688
Impairment of strategic investment	9,004
Amortization of non-cash interest	9,920	10,882
Stock-based compensation	10,994	15,411
Reserves on current assets	9,444	64
Other non-cash adjustments	12,133	7,380
Deferred income taxes	(6,593)	(3,077)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable	852	(15,823)
Inventory	(19,615)	(29,417)
Contingent consideration liabilities	(100)	(11,200)
Prepaid expenses and other current assets	(2,141)	(2,543)
Accounts payable and accrued liabilities	9,031	4,868
Accrued payroll and related expenses	(6,358)	(2,059)
Litigation liability	2,150
Income taxes	(53)	10,172
Net cash provided by operating activities	77,218	67,064
Investing activities:
Acquisitions and investments	(52,081)	(14,417)
Purchases of intangible assets	(7,682)	(1,695)
Purchases of property and equipment	(53,388)	(68,690)
Net cash used in investing activities	(113,151)	(84,802)
Financing activities:
Proceeds from the issuance of common stock	5,312	5,369
Purchase of treasury stock	(2,222)	(10,844)
Payment of contingent consideration	(8,900)	(18,800)
Proceeds from revolving line of credit	82,000	20,000
Repayments on revolving line of credit	(45,000)
Other financing activities	(146)	(2,205)
Net cash provided by (used in) financing activities	31,044	(6,480)
Effect of exchange rate changes on cash	(837)	1,449
Decrease in cash, cash equivalents, restricted cash and investments	(5,726)	(22,769)
Cash, cash equivalents, restricted cash and investments at beginning of period	78,198	161,048
Cash, cash equivalents, restricted cash and investments at end of period	$ 72,472	$ 138,279

Consolidated Statements of Cas7

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Statement Of Cash Flows [Abstract]
Cash and cash equivalents	$ 70,078	$ 72,803	$ 130,932
Restricted cash and investments, current		3,901	2,402
Restricted cash and investments, non-current	2,394	1,494	4,945
Total cash, cash equivalents, restricted cash and investments shown in the Unaudited Consolidated Statement of Cash Flows	$ 72,472	$ 78,198	$ 138,279	$ 161,048

Description of Business and Bas

Description of Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Description of Business NuVasive, Inc. (the “Company” or “NuVasive”) was incorporated in Delaware on July 21, 1997, and began commercializing its products in 2001. The Company’s principal product offering includes a minimally-disruptive surgical platform called Maximum Access Surgery, or MAS. The MAS platform combines three categories of solutions that collectively minimize soft tissue disruption during spine fusion surgery, provide maximum visualization and are designed to enable safe and reproducible outcomes for the surgeon and the patient. The platform includes the Company’s proprietary software-driven nerve detection and avoidance systems and Intraoperative Monitoring (“IOM”) services and support; MaXcess, an integrated split-blade retractor system; and a wide variety of specialized implants and biologics. To assist with surgical procedures the Company offers a technology platform called Integrated Global Alignment (“iGA”); in which products and computer assisted technology under the MAS platform help achieve more precise spinal alignment. The individual components of the MAS platform, and many of the Company’s products, can also be used in open or traditional spine surgery. The Company continues to focus research and development efforts to expand its MAS product platform and advance the applications of its unique technology into procedurally-integrated surgical solutions. The Company dedicates significant resources toward training spine surgeons on its unique technology and products. The Company’s procedurally integrated solutions use innovative, technological advancements and the MAS platform to provide surgical efficiency, operative reliability, and procedural versatility. The Company offers a range of implants for spinal surgery, which include its branded CoRoent products and porous titanium and polyetheretherketone implants under its Advanced Materials Science portfolio, fixation devices such as customizable rods, plates and screws, bone allograft in patented saline packaging, allogeneic and synthetic biologics, and disposables used in IOM. The Company makes available MAS instrument sets, MaXcess and neuromonitoring systems to hospitals to facilitate surgeon access to the spine to perform restorative and fusion procedures using the Company’s implants and fixation devices. The Company sells MAS instrument sets, MaXcess and neuromonitoring systems to hospitals, however, such sales are immaterial to the Company’s results of operations. The Company also designs and sells expandable growing rod implant systems that can be non-invasively lengthened following implantation with precise, incremental adjustments via an external remote controller using magnetic technology called MAGnetic External Control, or MAGEC, which allows for the minimally invasive treatment of early-onset and adolescent scoliosis. This technology is also the basis for the Company’s PRECICE limb lengthening system, which allows for the correction of long bone limb length discrepancy, as well as enhanced bone healing in patients that have experienced traumatic injury. The Company intends to continue development on a wide variety of projects intended to broaden surgical applications for greater procedural integration of its MAS techniques and additional applications of the MAGEC technology. Such applications include tumor, trauma, and deformity, as well as increased fixation options, sagittal alignment products, imaging and navigation. The Company also expects to continue expanding its other product and services offerings as it executes on its strategy to offer customers an end-to-end, procedurally integrated solution for spine surgery. The Company intends to continue to pursue business and technology acquisition targets and strategic partnerships. Basis of Presentation and Principles of Consolidation The accompanying Unaudited Consolidated Financial Statements include the accounts of the Company and its majority-owned or controlled subsidiaries, collectively referred to as either NuVasive or the Company. The Company translates the financial statements of its foreign subsidiaries using end-of-period exchange rates for assets and liabilities and average exchange rates during each reporting period for results of operations. When there is a portion of equity in an acquired subsidiary not attributable, directly or indirectly, to the respective parent entity, the Company records the fair value of the non-controlling interest at the acquisition date and classifies the amounts attributable to non-controlling interest separately in equity in the Company's Consolidated Financial Statements. Any subsequent changes in a parent's ownership interest while the parent retains its controlling financial interest in its subsidiary are accounted for as equity transactions. All significant intercompany balances and transactions have been eliminated in consolidation. The accompanying Unaudited Consolidated Financial Statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Pursuant to these rules and regulations, the Company has condensed or omitted certain information and footnote disclosures it normally includes in its annual Consolidated Financial Statements prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). Operating results for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for any other interim period or for the full year. These Unaudited Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and notes thereto for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC. In the opinion of management, the Unaudited Consolidated Financial Statements and notes thereto include all adjustments that are of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position and of the results of operations and cash flows for the periods presented. The Company has reclassified historically presented revenue and cost of revenue to conform to the current year presentation, which now reflects revenue and costs allocated to the Company’s product and service offerings. T Revenue from Contracts with Customers (“ASU 2014-09”) on January 1, 2018 adopted Accounting Standards Codification 606 Revenue from Contracts with Customers (“ASC 606”), electing full retrospective method of adoption. Use of Estimates To prepare financial statements in conformity with GAAP, management must make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Recent Accounting Pronouncements Not Yet Adopted In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2016-02, Leases, which introduced ASC 842 – Leases, a new comprehensive lease accounting model that supersedes the current lease guidance under ASC 840 – Leases . The new accounting standard requires lessees to recognize right-of-use assets and corresponding lease liabilities for all leases with lease terms of greater than twelve months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. The new accounting standard must be adopted using the modified retrospective approach and will be effective for the Company starting in the first quarter of fiscal 2019. Early adoption is permitted. The Company is in the process of determining the impact the adoption will have on its Consolidated Financial Statements and expects significant changes relating to the recognition of right-of-use assets and liabilities associated with its operating leases. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments – Credit Losses The Company believes the adoption will modify the way the Company analyzes financial instruments, but it does not anticipate a material impact on results of operations. In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles – Goodwill and Other In July 2017, the FASB issued Accounting Standards Update No. 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging early adoption is permitted. In August 2017, the FASB issued Accounting Standards Update No. 2017-12, Derivatives and Hedging In March 2018, the FASB issued Accounting Standards Update No. 2018-05, Income taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 In June 2018, the FASB issued Accounting Standards Update No. 2018-07, Compensation – Stock Compensation Recently Adopted Accounting Standards In May 2014, the FASB issued Accounting Standard Update No. 2014-09 Revenue from Contracts with Customers Prior to the adoption of ASC 606, the Company recognized revenue in accordance with ASC 605 when all four of the following criteria were met: (i) persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured. Specifically, revenue from the sale of implants, biologics and disposables was generally recognized upon a purchase order from the hospital or acknowledgment from the hospital indicating product use or implantation or upon shipment to third-party customers who immediately accepted title. Revenue from the sale of instrument sets was recognized upon receipt of a purchase order and the subsequent shipment to customers who immediately accepted title. Revenue from neuromonitoring services was recognized in the period the service was performed for the amount of payment expected to be received. The Company adopted ASC 606 as of January 1, 2018, electing full retrospective method of adoption, which resulted in a change in its accounting policy for revenue recognition and related adjustments to the Consolidated Financial Statements for all periods presented. The Company applied the practical expedients permitted under ASC 606 for which (i) contracts with customers originating prior to January 1, 2016 do not require disclosure for the amount of consideration allocated to remaining performance obligations or an explanation of when the Company expects to recognize that amount as revenue; (ii) contracts beginning and completing in the same annual reporting period need not be restated; and (iii) hindsight for estimating variable consideration for completed contracts is permitted. The Company recognizes revenue from spinal surgery hardware and ancillary products at a point in time in two types of transactions: (i) procedural based transactions with products used during surgery defined as “charge sheet orders”, and (ii) shipping transactions which represent the stocking of product or the purchase of instrumentation to support future surgeries defined as “stocking and capital orders”. The Company also recognizes revenue at a point in time associated with surgical-related servicing procedures, including neuromonitoring services which are defined as “surgical-related services”. Other sources of revenue, such as leasing revenue and royalties, are immaterial to the Consolidated Financial Statements. For charge sheet orders, the sale occurs when the surgery is performed and a charge sheet is submitted to the Company by its sales representative identifying the products consumed during the surgery. The charge sheet, as signed by the hospital, serves as a confirmation and acknowledgement of the Company’s products consumed during a surgery. Under ASC 605, persuasive evidence of an arrangement and delivery of product was deemed to have occurred once the charge sheet was processed, and an associated authorization or acknowledgement from the customer was received. Under ASC 606, the Company’s charge sheet orders are considered to be a contract with a customer when a surgery is scheduled with the Company as requested by the hospital or surgeon, and the products are consumed during the surgery or implanted into the patient. Revenue recognition under ASC 606 occurs upon completion of the Company’s performance obligation, which occurs upon consumption of the products during surgery and receipt of the charge sheet. In the event that information related to the surgical event and consumption of product is not readily available the Company recognizes revenue upon a purchase order from the hospital or acknowledgment from the hospital indicating product use. For stocking and capital orders, under ASC 605, delivery was deemed to have occurred when the title, including all risks and rewards of ownership of the products specified in the sales agreement had passed to the buyer. Accordingly, title, including all risks and rewards of ownership, passed based on the shipping terms. Under ASC 606, the Company’s stocking and capital order performance obligation is considered to be satisfied when the hospital assumes control of the asset, either upon shipment or delivery depending on the terms, and ability to direct the use of the asset as appropriate without the Company’s consent. Under both ASC 605 and ASC 606, revenue from surgical-related services, such as neuromonitoring services, is recognized in the period the service is performed based on the delivery of a services report to the customer. The Company recognizes revenue for the amount of payment expected to be received. The Company bills either hospitals or insurance companies for different aspects of the service, as applicable. Revenue from hospitals is recognized based on agreed upon pricing. Revenue from insurance companies is recognized using the expected value method, as the Company bills at a gross rate which is generally not the rate ultimately collected. Under ASC 605, the Company has historically estimated the amounts of returns, trade-ins, discounts, rebates, credits or incentives as offsets to the total transaction price or revenue associated with the sale. In limited situations, when historical information was not available or reliable, the Company would defer revenue recognition until completion of all performance obligations. Under ASC 606, the Company analyzes sales that could include variable consideration, and estimates the expected or most likely amount of revenue after returns, trade-ins, discounts, rebates, credits, and incentives. In making these estimates, the Company considers whether the amount of variable consideration is constrained and is included in revenue only to the extent that it is probable that a significant reversal of the revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company earns sales-based royalty revenue over time from sales of products using existing biologics intellectual property (“IP”) that is out-licensed to certain companies. Under ASC 605, royalty revenue was recognized as earned and when collection was reasonably assured and was generally estimated and recorded in the same period as the sales that generated the royalty obligation. ASC 606 provides an exception for sales or usage-based royalties from the guidance for accounting for variable consideration, allowing the royalty revenue from the license of IP to be recognized when the performance obligation has been satisfied and the subsequent sale has occurred. Therefore, the Company estimates monthly royalty revenue as its performance obligation is satisfied. The Company does not expect a significant impact to royalty revenue under the adoption of ASC 606 as it has historically estimated and accrued royalty revenue in the period earned. The Company historically expensed incremental costs, such as commissions associated with sales contracts, as incurred. Under ASU 2014-09, ASC 340-40 Other Assets and Deferred Costs was added along with ASC 606 to codify accounting guidance for the incremental costs to obtain or fulfill a contract with a customer. Under the guidance, the incremental costs must be deferred and recorded over the period in which the contract revenue is recognized. The Company typically does not associate quarterly or annual sales bonuses directly with a sale or master contract; however, commissions are directly associated with individual sales and expensed in the same period as the related contract revenue. The associated commissionable sales would not typically have a future benefit unless the revenue is recognized over time. The Company does not typically have situations where revenue is deferred in excess of one year. Given the practical expedient for contracts completing within one year, the Company does not expect these capitalized costs to be material in a given period. The cumulative effect of the change on retained earnings for the full retrospective method of adoption of ASC 606 was $0.3 million as of December 31, 2017. NUVASIVE, INC. CONSOLIDATED BALANCE SHEET (in thousands) (Unaudited) (Unaudited) As of December 31, 2017 As reported Adjustments As Adjusted Accounts receivable, gross $ 212,709 $ 537 [a] $ 213,246 Allowances on accounts receivable (13,669 ) 643 [b] (13,026 ) Inventory, net 247,245 (107 ) [c] 247,138 Other current assets 112,705 — 112,705 Total current assets 558,990 1,073 560,063 Remaining other assets 1,080,077 — 1,080,077 Total assets $ 1,639,067 $ 1,073 $ 1,640,140 Accounts payable and accrued liabilities 75,076 691 [d] 75,767 Accrued payroll and related expenses 55,582 36 [e] 55,618 Other current liabilities 30,010 — 30,010 Total current liabilities 160,668 727 161,395 Deferred and income tax liabilities, non-current 18,786 84 [f] 18,870 Other long-term liabilities 660,459 — 660,459 Total NuVasive, Inc. stockholders’ equity 795,309 262 [g] 795,571 Non-controlling interests 3,845 — 3,845 Total equity 799,154 262 799,416 Total liabilities and equity $ 1,639,067 $ 1,073 $ 1,640,140 [a] Represents cumulative impact from January 1, 2016 to the period presented on accounts receivable for the full retrospective method of adoption of ASC 606. [b] Represents cumulative impact from January 1, 2016 to the period presented on allowances on accounts receivable for the full retrospective method of adoption of ASC 606. [c] Represents cumulative impact from January 1, 2016 to the period presented on inventory for the full retrospective method of adoption of ASC 606. [d] Represents cumulative impact from January 1, 2016 to the period presented on commissions payable and accrued returns for the full retrospective method of adoption of ASC 606. [e] Represents cumulative impact from January 1, 2016 to the period presented on commissions payable for the full retrospective method of adoption of ASC 606. [f] Represents cumulative impact from January 1, 2016 to the period presented on deferred tax liabilities for the full retrospective method of adoption of ASC 606. [g] Represents cumulative impact from January 1, 2016 to the period presented on retained earnings for the full retrospective method of adoption of ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (in thousands, except per share amounts) (Unaudited) As reported Adjustments As adjusted Three months ended June 30, 2017 Revenue Product revenue $ 238,998 $ (1,174 ) [a] $ 237,824 Service revenue 21,575 — 21,575 Total revenue 260,573 (1,174 ) 259,399 Cost of revenue (excluding amortization of intangible assets) Cost of products sold 50,770 (235 ) [b] 50,535 Cost of services 15,651 — 15,651 Total cost of revenue 66,421 (235 ) 66,186 Gross profit 194,152 (939 ) 193,213 Operating expenses: Sales, marketing and administrative 139,109 (142 ) [c] 138,967 Other operating expenses 25,290 — 25,290 Total operating expenses 164,399 (142 ) 164,257 Total interest and other expense, net (10,445 ) — (10,445 ) Income tax (expense) benefit (7,079 ) 303 [d] (6,776 ) Consolidated net income $ 12,229 $ (494 ) [e] $ 11,735 Add back net loss attributable to non-controlling interests $ (432 ) $ — $ (432 ) Net income attributable to NuVasive, Inc. $ 12,661 $ (494 ) [e] $ 12,167 Net income per share attributable to NuVasive, Inc.: Basic $ 0.25 $ (0.01 ) [f] $ 0.24 Diluted $ 0.22 $ (0.01 ) [f] $ 0.21 Comprehensive income attributable to NuVasive, Inc. $ 13,304 $ (494 ) [e] $ 12,810 [a] Represents net change in sales revenue for charge sheet orders recognized under ASC 606. [b] Represents net change in cost of products sold for charge sheet orders recognized under ASC 606. [c] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. [d] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [e] Represents change in net income and comprehensive income resulting from net change in charge sheet orders recognized under ASC 606. [f] Represents earnings per share impact resulting from net change in charge sheet orders recognized under ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (in thousands, except per share amounts) (Unaudited) As reported Adjustments As adjusted Six months ended June 30, 2017 Revenue Product revenue $ 464,804 $ (2,025 ) [a] $ 462,779 Service revenue 45,633 — 45,633 Total revenue 510,437 (2,025 ) 508,412 Cost of revenue (excluding amortization of intangible assets) Cost of products sold 96,841 (405 ) [b] 96,436 Cost of services 31,193 — 31,193 Total cost of revenue 128,034 (405 ) 127,629 Gross profit 382,403 (1,620 ) 380,783 Operating expenses: Sales, marketing and administrative 279,611 (276 ) [c] 279,335 Other operating expenses 49,820 — 49,820 Total operating expenses 329,431 (276 ) 329,155 Total interest and other expense, net (19,849 ) — (19,849 ) Income tax (expense) benefit (8,569 ) 508 [d] (8,061 ) Consolidated net income $ 24,554 $ (836 ) [e] $ 23,718 Add back net loss attributable to non-controlling interests $ (875 ) $ — $ (875 ) Net income attributable to NuVasive, Inc. $ 25,429 $ (836 ) [e] $ 24,593 Net income per share attributable to NuVasive, Inc.: Basic $ 0.50 $ (0.02 ) [f] $ 0.48 Diluted $ 0.44 $ (0.01 ) [f] $ 0.42 Comprehensive income attributable to NuVasive, Inc. $ 27,929 $ (836 ) [e] $ 27,093 [a] Represents net change in sales revenue for charge sheet orders recognized under ASC 606. [b] Represents net change in cost of products sold for charge sheet orders recognized under ASC 606. [c] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. [d] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [e] Represents change in net income and comprehensive income resulting from net change in charge sheet orders recognized under ASC 606. [f] Represents earnings per share impact resulting from net change in charge sheet orders recognized under ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF CASH FLOWS (in thousands) (Unaudited) Six months ended June 30, 2017 As reported Adjustments As adjusted Consolidated net income $ 24,554 $ (836 ) [a] $ 23,718 Adjustments to reconcile net income to net cash provided by operating activities: Reserves on current assets (95 ) 159 [b] 64 Deferred income tax benefit (2,570 ) (507 ) [c] (3,077 ) Other adjustments to reconcile net income 92,361 — 92,361 Changes in operating assets and liabilities, net of effects from acquisitions: Accounts receivable (17,586 ) 1,763 [d] (15,823 ) Inventory (29,012 ) (405 ) [e] (29,417 ) Prepaid expenses and other current assets (2,543 ) — (2,543 ) Accounts payable and accrued liabilities 4,987 (119 ) [f] 4,868 Litigation liability (11,200 ) — (11,200 ) Accrued payroll and related expenses (2,004 ) (55 ) [f] (2,059 ) Income taxes 10,172 — 10,172 Net cash provided by operating activities 67,064 — 67,064 Net cash used in investing activities (84,802 ) — (84,802 ) Net cash used in financing activities (6,480 ) — (6,480 ) Effect of exchange rate changes on cash 1,449 — 1,449 Decrease in cash, cash equivalents and restricted cash $ (22,769 ) $ — $ (22,769 ) [a] Represents change in net income resulting from charge sheet orders recognized under ASC 606. [b] Represents net change in allowances on accounts receivable for charge sheet orders recognized under ASC 606. [c] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [d] Represents net change in accounts receivable for charge sheet orders recognized under ASC 606. [e] Represents net change in inventory for charge sheet orders recognized under ASC 606. [f] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. In January 2016, the FASB issued Accounting Standards Update No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities provides a practicability exception for investments that do not have readily determinable fair values, practicability exception for measuring equity investments that do not have readily determinable fair market In August 2016, the FASB issued Accounting Standards Update No. 2016-15, Classification of Certain Cash Receipts and Cash Payments In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Restricted Cash In January 2017, the FASB issued Accounting Standards Update No. 2017-01, Clarifying the Definition of a Business In February 2017, the FASB issued Accounting Standards Update No. 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets In May 2017, the FASB issued Accounting Standards Update No. 2017-09, Compensation – Stock Compensation Revenue Recognition In accordance with ASC 606 guidance, the Company recognizes revenue upon the transfer of goods or services to a customer at an amount that reflects the expected consideration to be received in exchange for those goods or services. The principles in ASC 606 are applied using the following five steps: dentify the contract with a customer dentify the performance obligation(s) in the contract etermine the transaction price llocate the transaction price to the performance obligation(s) in the contract; ecognize revenue when (or as) the Company satisfies its performance obligation(s) Revenue from neuromonitoring services is recognized in the period the service is performed for the amount of consideration expected to be received. In certain cases, the Company does offer the ability for customers to lease instrumentation primarily on a non-sales type basis. Revenue associated with products holding rights of return or trade-in are recognized when the Company concludes there is not a risk of significant revenue reversal in future periods for the expected consideration in the transaction. Costs incurred by the Company associated with sales contracts with customers are deferred over the performance obligation period and recognized in the same period as the related revenue, with the exception of contracts that complete within one year or less, in which case the associated costs are expensed as incurred. Inventory Net inventory as of June 30, 2018 primarily consisted of $244.4 million of finished goods, $10.2 million of work in progress and $5.2 million of raw materials. Net inventory as of December 31, 2017 consisted of $232.4 million of finished goods, $9.8 million of work in progress and $5.0 million of raw materials. Finished goods include specialized implants and disposables and are stated at the lower of cost or market determined by utilizing a standard cost method, which includes assessment of capitalized variances, which approximates the weighted average cost. Work in progress and raw materials represent the underlying material, and labor for work in progress, that ultimately yield finished goods upon completion and are subject to lower of cost or market. The Company reviews the components of its inventory on a periodic basis for excess and obsolescence and adjusts inventory to its net realizable value as necessary. Comprehensive Income Comprehensive income is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive income includes net of tax, unrealized gains or losses on the Company’s marketable securities and foreign currency translation adjustments. The cumulative translation adjustments included in accumulated other comprehensive loss were $8.9 million and $6.9 million at June 30, 2018 and December 31, 2017, respectively. Product Shipment Costs Product shipment costs, included in sales, marketing and administrative expense in the accompanying Consolidated Statements of Operations, were $6.4 million and $12.3 million for the three and six months ended June 30, 2018, respectively, and $5.7 million and $11.6 million for the three and six months ended June 30, 2017, respectively. The majority of the Company’s shipping costs are related to the loaning of instrument sets, which are not typically sold as part of the Company’s core sales offering. Amounts billed to customers for shipping and handling of products are reflected in revenues and are not material for any period presented . Business Transition Costs The Company incurs certain costs related to acquisition, integration and business transition activities, which include severance, relocation, consulting, leasehold exit costs, third-party merger and acquisition costs, contingent consideration fair value adjustments and other costs directly associated with such activities. The Company incurred $4.0 million and $6.3 million of such costs during the three and six months ended June 30, 2018, respectively, which consisted primarily of acquisition, integration and business transition activities, but also includes $0.6 million and $0.8 million, respectively, of fair value adjustments on contingent consideration liabilities associated with the Company’s 2017 and 2016 acquisitions. During both the three and six months ended June 30, 2017, the Company incurred $1.4 million of such costs, which included $0.7 million and $(0.7) million, respectively, of fair value adjustments on contingent consideration liabilities associated with the Company’s 2017 and 2016 acquisitions, and other costs related to acquisition, integration and business transition activities.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	2. Net Income (Loss) Per Share The following table sets forth the computation of basic and diluted net income (loss) per share attributable to the Company: Three Months Ended June 30, Six Months Ended June 30, ( in thousands, except per share data 2018 2017 2018 2017 Numerator: Net income (loss) attributable to NuVasive, Inc. $ 11,531 $ 12,167 $ (15,601 ) $ 24,593 Denominator for basic and diluted net income (loss) per share: Weighted average common shares outstanding for basic 51,356 51,082 51,292 50,825 Dilutive potential common stock outstanding: Stock options and employee stock purchase plan 30 138 — 180 Restricted stock units 570 1,356 — 1,386 Warrants — 2,929 — 2,987 Senior Convertible Notes — 2,825 — 2,681 Weighted average common shares outstanding for diluted 51,956 58,330 51,292 58,059 Basic net income (loss) per share attributable to NuVasive, Inc. $ 0.22 $ 0.24 $ (0.30 ) $ 0.48 Diluted net income (loss) per share attributable to NuVasive, Inc. $ 0.22 $ 0.21 $ (0.30 ) $ 0.42 The following weighted-average outstanding common stock equivalents were not included in the calculation of net income (loss) per diluted share because their effects were anti-dilutive: Three Months Ended June 30, Six Months Ended June 30, ( in thousands 2018 2017 2018 2017 Stock options, employee stock purchase plan, and restricted stock units 161 41 1,281 71 Warrants 10,865 10,865 10,865 10,865 Senior Convertible Notes 10,865 — 10,865 — Total 21,891 10,906 23,011 10,936

Financial Instruments and Fair

Financial Instruments and Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Investments Debt And Equity Securities [Abstract]
Financial Instruments and Fair Value Measurements	3. Financial Instruments and Fair Value Measurements Foreign Currency and Derivative Financial Instruments The Company translates the financial statements of its foreign subsidiaries using end-of-period exchange rates for assets and liabilities and average exchange rates during each reporting period for results of operations. Some of the Company’s reporting entities conduct a portion of their business in currencies other than the entity’s functional currency. These transactions give rise to receivables and payables that are denominated in currencies other than the entity’s functional currency. The value of these receivables and payables is subject to changes in currency exchange rates from the point at which the transactions are originated until the settlement in cash. Both realized and unrealized gains and losses in the value of these receivables and payables are included in the determination of net income. Net currency exchange (losses) gains, which include gains and losses from derivative instruments, were $(2.2) million and $(2.5) million for the three and six months ended June 30, 2018, respectively, and $(0.5) million and $(0.3) million for the three and six months ended June 30, 2017, respectively, and are included in other expense, net in the Consolidated Statements of Operations. To manage foreign currency exposure risks, the Company uses derivatives for activities in entities that have short-term intercompany receivables and payables denominated in a currency other than the entity’s functional currency. A s of June 30, 2018 and December 31, 2017 a notional principal amount of $15.9 million and $ 14.3 million, respectively, was outstanding to hedge currency risk relative to the Company’s foreign receivables and payables . Derivative instrument net gains (losses) on the Company’s forward exchange contracts were $0.7 million and $0.3 million for the three and six months ended June 30, 2018, respectively, and $(0.9) million and $(1.3) million for the three and six months ended June 30, 2017, respectively, and are included in other expense, net in the Consolidated Statements of Operations. The fair value of the forward contract exchange derivative instrument liability was $(0.1) million as of June 30, 2018 and December 31, 2017. The derivative instruments are recorded in other current assets or other current liabilities in the Consolidated Balance Sheets commensurate with the nature of the instrument at period end. Fair Value Measurements The Company measures certain assets and liabilities in accordance with authoritative guidance which requires fair value measurements be classified and disclosed in one of the following three categories: Level 1: Quoted prices (unadjusted) in active markets that are accessible at the measurement date for assets or liabilities. Level 2: Observable prices that are based on inputs not quoted on active markets, but corroborated by market data. Level 3: Unobservable inputs are used when little or no market data is available. Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. The Company reviews the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels for certain assets or liabilities within the fair value hierarchy. The Company did not have any transfers of assets and liabilities between the levels of the fair value measurement hierarchy during the periods presented. The fair values of the Company’s assets and liabilities, including cash equivalents, marketable securities, restricted investments, derivatives, and contingent obligations are measured at fair value on a recurring basis. As of June 30, 2018 and December 31, 2017, the Company held investments in securities classified as cash equivalents. During the periods presented, the Company did not hold any investments that were in a significant unrealized loss position and no impairment charges were recorded. Realized gains and losses and interest income related to marketable securities were immaterial during all periods presented. Cash equivalents are determined under the fair value categories as follows: Quoted Price in Significant Other Significant Active Market Observable Inputs Unobservable ( in thousands Total (Level 1) (Level 2) Inputs (Level 3) June 30, 2018: Cash equivalents: Money market funds $ 20,000 $ 20,000 $ — $ — Total cash equivalents $ 20,000 $ 20,000 $ — $ — December 31, 2017: Cash equivalents: Money market funds $ 27,000 $ 27,000 $ — $ — Total cash equivalents $ 27,000 $ 27,000 $ — $ — The carrying amounts of certain financial instruments such as cash equivalents, accounts receivable, prepaid expenses, other current assets, accounts payable, accrued expenses, and other current liabilities as of June 30, 2018 and December 31, 2017 approximate their related fair values due to the short-term maturities of these instruments. The fair value of certain financial instruments was measured and classified within Level 1 of the fair value hierarchy based on quoted prices. Fair Value of Senior Convertible Notes The fair value, based on a quoted market price (Level 1), of the Company’s outstanding Senior Convertible Notes due 2021 at June 30, 2018 and December 31, 2017, was $710.9 million and $779.5 million, respectively. See Note 6 to the Unaudited Consolidated Financial Statements for further discussion on the carrying value of the notes. Contingent Consideration Liabilities The fair value of contingent consideration liabilities assumed in business combinations is recorded as part of the purchase price consideration of the acquisition, and is determined using a discounted cash flow model or probability simulation model. The significant inputs of such models are not observable in the market, such as certain financial metric growth rates, volatility rates, projections associated with the applicable milestone, the interest rate, and the related probabilities and payment structure in the contingent consideration arrangement. Fair value adjustments to contingent consideration liabilities are recorded through operating expenses in the Consolidated Statement of Operations. Contingent consideration arrangements assumed by an asset purchase will be measured and accrued when such contingency is resolved. Contingent consideration liabilities were $66.4 million and $67.9 million as of June 30, 2018 and December 31, 2017, respectively, and were recorded in the Consolidated Balance Sheet commensurate with the respective payment terms. The following table sets forth the changes in the estimated fair value of the Company’s liabilities measured on a recurring basis using significant unobservable inputs (Level 3): Six Months Ended June 30, ( in thousands 2018 2017 Fair value measurement at beginning of period $ 67,941 $ 67,501 Contingent consideration liability recorded upon acquisition 6,663 533 Change in fair value measurement 794 (657 ) Changes resulting from foreign currency fluctuations 25 44 Contingent consideration paid or settled (9,000 ) (30,000 ) Fair value measurement at end of period $ 66,423 $ 37,421 Non-financial assets and liabilities measured on a nonrecurring basis Certain non-financial assets and liabilities are measured at fair value, usually with Level 3 inputs including the discounted cash flow method or cost method, on a nonrecurring basis in accordance with authoritative guidance. These include items such as non-financial assets and liabilities initially measured at fair value in a business combination and non-financial long-lived assets measured at fair value for an impairment assessment. In general, non-financial assets, including goodwill, intangible assets and property and equipment, are measured at fair value when there is an indication of impairment and are recorded at fair value only when any impairment is recognized. The carrying values of the Company’s capital lease obligations approximated their estimated fair value as of June 30, 2018 and December 31, 2017. During the six months ended June 30, 2018, the Company recorded an impairment charge of $9.0 million on a strategic investment. The impairment was recorded in other expense, net in the Unaudited Consolidated Statement of Operations.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	4. Goodwill and Intangible Assets Goodwill and intangible assets consisted of the following: Weighted- Average Amortization ( in thousands, except years Period Gross Accumulated Intangible June 30, 2018: (in years) Amount Amortization Assets, net Intangible assets subject to amortization: Developed technology 8 $ 271,748 $ (115,442 ) $ 156,306 Manufacturing know-how and trade secrets 13 30,831 (16,728 ) 14,103 Trade name and trademarks 9 25,500 (12,218 ) 13,282 Customer relationships 9 143,847 (51,220 ) 92,627 Total intangible assets subject to amortization 9 $ 471,926 $ (195,608 ) $ 276,318 Intangible assets not subject to amortization: Goodwill $ 560,751 Total goodwill and intangible assets, net $ 837,069 Weighted- Average Amortization Period Gross Accumulated Intangible December 31, 2017: (in years) Amount Amortization Assets, net Intangible assets subject to amortization: Developed technology 8 $ 271,748 $ (98,693 ) $ 173,055 Manufacturing know-how and trade secrets 13 30,653 (15,542 ) 15,111 Trade name and trademarks 9 25,200 (10,559 ) 14,641 Customer relationships 9 122,249 (44,282 ) 77,967 Total intangible assets subject to amortization 9 $ 449,850 $ (169,076 ) $ 280,774 Intangible assets not subject to amortization: Goodwill $ 536,926 Total goodwill and intangible assets, net $ 817,700 The following table summarizes the changes in the carrying value of the Company’s goodwill: ( in thousands December 31, 2017 Gross goodwill $ 545,226 Accumulated impairment loss (8,300 ) 536,926 Changes to gross goodwill Increases recorded in business combinations 26,303 Changes in purchase price allocation (1,075 ) Changes resulting from foreign currency fluctuations (1,403 ) 23,825 June 30, 2018 Gross goodwill 569,051 Accumulated impairment loss (8,300 ) $ 560,751 Total expense related to the amortization of intangible assets, which is recorded in both cost of revenue and operating expenses in the Consolidated Statements of Operations depending on the functional nature of the intangible asset, was $13.5 million and $26.9 million for the three and six months ended June 30, 2018, respectively, and $12.2 million and $25.2 million for the three and six months ended June 30, 2017, respectively. Total future amortization expense related to intangible assets subject to amortization at June 30, 2018 is set forth in the table below: ( in thousands Remaining 2018 $ 26,406 2019 51,638 2020 51,016 2021 48,956 2022 41,545 Thereafter through 2031 56,757 Total future amortization expense $ 276,318

Business Combinations

Business Combinations	6 Months Ended
	Jun. 30, 2018
Business Combination Description [Abstract]
Business Combinations	5. Business Combinations The Company recognizes the assets acquired, liabilities assumed, and any non-controlling interest at fair value at the date of acquisition. Certain acquisitions contained contingent consideration arrangements that required the Company to assess the acquisition date fair value of the contingent consideration liabilities, which was recorded as part of the purchase price allocation of the acquisition, with subsequent fair value adjustments to the contingent consideration recorded in the Consolidated Statements of Operations. See Note 3 Acquisitions In January 2018, the Company acquired SafePassage, a privately-held provider of IOM services, which now operates as a wholly-owned subsidiary of the Company. The acquisition was not considered material to the overall Unaudited Consolidated Financial Statements. The Company’s NuVasive Clinical Services division (including SafePassage) represents the reported service revenue on the Unaudited Consolidated Statement of Operations. The Company has completed other acquisitions that were not considered material, individually or collectively, to the overall Unaudited Consolidated Financial Statements during the periods presented. These acquisitions have been included in the Unaudited Consolidated Financial Statements from the respective dates of acquisition. The Company does not believe that collectively the acquisitions made during the periods presented are material to the overall financial statements. For certain acquisitions completed during the periods presented, the Company is still in the process of finalizing the purchase price allocation given the timing of the acquisitions and the size and scope of the assets and liabilities subject to valuation. While the Company does not expect material changes in the valuation outcome, certain assumptions and findings that were in place at the date of acquisition could result in changes in the purchase price allocation. Variable Interest Entities Progentix Orthobiology B.V. In 2009, the Company purchased forty percent (40%) of the capital stock of Progentix Orthobiology B.V. (“Progentix”), a company organized under the laws of the Netherlands, from existing shareholders pursuant to a Preferred Stock Purchase Agreement for $10.0 million in cash (the “Initial Investment”). The Company also loaned Progentix cumulatively a total of $5.3 million at an interest rate of 6% per year (the “Loan”) . for a term of ten years, whereby Progentix appointed the Company as its exclusive distributor for certain Progentix products. Following the Initial Investment, in accordance with authoritative guidance, the Company determined that Progentix was a variable interest entity (“VIE”), as it did not have the ability to finance its activities without additional subordinated financial support and its equity investors would not absorb their proportionate share of expected losses and would be limited in the receipt of the potential residual returns of Progentix. In January 2018, the Company completed the acquisition of the remaining 60% of the capital stock of Progentix (the “Non-Controlling Interest Acquisition”). Subsequent to the Non-Controlling Interest Acquisition, the Company owns 100% of the capital stock of Progentix, which now operates as its wholly-owned subsidiary and is no longer accounted for as a VIE or a separate reporting unit as of the date of the Non-Controlling Interest Acquisition. In accordance with authoritative guidance, The following is a reconciliation of equity (net assets) attributable to the non-controlling interest: Six Months Ended June 30, ( in thousands 2018 2017 Non-controlling interest at beginning of period $ 3,845 $ 5,588 Acquired non-controlling interest reclassified to additional paid-in capital (3,845 ) — Less: Net loss attributable to the non-controlling interest — (875 ) Non-controlling interest at end of period $ — $ 4,713 Total assets and liabilities of Progentix as a VIE included in the accompanying Consolidated Balance Sheets are as follows: ( in thousands June 30, 2018 December 31, 2017 Total current assets $ — $ 670 Identifiable intangible assets, net — 8,752 Goodwill — 12,654 Accounts payable and accrued expenses — 562 Deferred tax liabilities, net — 331 Non-controlling interest — 3,845 NuVasive Clinical Services and Physician Practices The Company’s NuVasive Clinical Services division (including SafePassage), which provides IOM services to surgeons and healthcare facilities across the U.S., maintain contractual relationships with several physician practices (“PCs”). In accordance with authoritative guidance, the Company has determined that the PCs are VIEs and therefore, the accompanying Unaudited Consolidated Financial Statements include the accounts of the PCs from the date of acquisition. During the periods presented, the results of the PCs were immaterial to the Company’s financials. The creditors of the PCs have claims only on the assets of the PCs, which are not material, and the assets of the PCs are not available to the Company.

Indebtedness

Indebtedness	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Indebtedness	6. Indebtedness The carrying values of the Company’s Senior Convertible Notes due 2021 are as follows: ( in thousands June 30, 2018 December 31, 2017 2.25% Senior Convertible Notes due 2021: Principal amount 650,000 650,000 Unamortized debt discount (48,587 ) (56,839 ) Unamortized debt issuance costs (8,832 ) (10,241 ) Total Senior Convertible Notes $ 592,581 $ 582,920 2.25% Senior Convertible Notes due 2021 In March 2016, the Company issued $650.0 million principal amount of unsecured Senior Convertible Notes with a stated interest rate of 2.25% and a maturity date of March 15, 2021 (the "2021 Notes"). The net proceeds from the offering, after deducting initial purchasers' discounts and costs directly related to the offering, were approximately $634.1 million. The 2021 Notes may be settled in cash, stock, or a combination thereof, solely at the Company's discretion. It is the Company's current intent and policy to settle all conversions through combination settlement, which involves satisfying the principal amount outstanding with cash and any note conversion value over the principal amount in shares of the Company's common stock. The initial conversion rate of the 2021 Notes is 16.7158 shares per $1,000 principal amount, which is equivalent to a conversion price of approximately $59.82 per share, subject to adjustments. The Company uses the treasury share method for assumed conversion of the 2021 Notes to compute the weighted average shares of common stock outstanding for diluted earnings per share. The Company also entered into transactions for a convertible note hedge (the "2021 Hedge") and warrants (the "2021 Warrants") concurrently with the issuance of the 2021 Notes. The cash conversion feature of the 2021 Notes required bifurcation from the notes and was initially accounted for as an equity instrument classified to stockholders’ equity, which resulted in recognizing $84.8 million in additional paid-in-capital during 2016. The interest expense recognized on the 2021 Notes during the three months ended June 30, 2018 June Prior to September 15, 2020, holders may convert their 2021 Notes only under the following conditions: (a) during any calendar quarter beginning June 30, 2016, if the reported sale price of the Company's common stock for at least 20 days out of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (b) during the five business day period in which the trading price of the 2021 Notes falls below 98% of the product of (i) the last reported sale price of the Company's common stock and (ii) the conversion rate on that date; and (c) upon the occurrence of specified corporate events, as defined in the 2021 Notes. From September 15, 2020 and until the close of business on the second scheduled trading day immediately preceding March 15, 2021, holders may convert their 2021 Notes at any time (regardless of the foregoing circumstances). The Company may not redeem the 2021 Notes prior to March 20, 2019. The Company may redeem the 2021 Notes, at its option, in whole or in part on or after March 20, 2019 until the close of business on the business day immediately preceding September 15, 2020 if the last reported sale price of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20 trading days during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company delivers written notice of a redemption. The redemption price will be equal to 100% of the principal amount of such 2021 Notes to be redeemed plus accrued and unpaid interest to, but excluding, the redemption date 2021 Hedge In connection with the offering of the 2021 Notes, the Company entered into the hedge transaction with the initial purchasers of the 2021 Notes and/or their affiliates (the "2021 Counterparties") entitling the Company to purchase up to 10,865,270 shares of the Company's common stock at an initial stock price of $59.82 per share, each of which is subject to adjustment. The cost of the 2021 Hedge was $111.2 million and accounted for as an equity instrument by recognizing $111.2 million in additional paid-in-capital during 2016. The 2021 Hedge will expire on March 15, 2021. The 2021 Hedge is expected to reduce the potential equity dilution upon conversion of the 2021 Notes if the daily volume-weighted average price per share of the Company's common stock exceeds the strike price of the 2021 Hedge. An assumed exercise of the 2021 Hedge by the Company is considered anti-dilutive since the effect of the inclusion would always be anti-dilutive with respect to the calculation of diluted earnings per share. 2021 Warrants The Company sold warrants to the 2021 Counterparties to acquire up to 10,865,270 shares of the Company’s common stock. The 2021 Warrants will expire on various dates from June 2021 through December 2021 and may be settled in cash or net shares. It is the Company's current intent and policy to settle all conversions in shares of the Company’s common stock. The Company received $44.9 million in cash proceeds from the sale of the 2021 Warrants, which was recorded in additional paid-in-capital. The 2021 Warrants could have a dilutive effect on the Company's earnings per share to the extent that the price of the Company's common stock during a given measurement period exceeds the strike price of the 2021 Warrants, which is $80.00 per share. The Company uses the treasury share method for assumed conversion of its 2021 Warrants to compute the weighted average common shares outstanding for diluted earnings per share. 2.75% Senior Convertible Notes due 2017 In June 2011, the Company issued $402.5 million 2.75% July 1, 2017 (the “2017 Notes”) 23.7344 $1,000 $42.13 During 2016, the Company repurchased a majority of the 2017 Notes, which resulted in a cumulative loss of approximately $19.1 million recorded in other expense on the accompanying Consolidated Statements of Operations for the year ended December 31, 2016. In July 2017, the Company settled the remaining 2017 Notes upon maturity via combination settlement, which involved satisfying the principal amount outstanding with cash and any note conversion value over the principal amount in shares of the Company’s common stock . The interest expense recognized on the 2017 Notes during the three months ended June 30, 2017 includes $0.4 million, $0.7 million and $0.1 million for the contractual coupon interest, the accretion of the debt discount and the amortization of the debt issuance costs, respectively. The interest expense recognized on the 2017 Notes during the six months ended June 30, 2017 includes $0.9 million, $1.4 million and $0.2 million for the contractual coupon interest, the accretion of the debt discount and the amortization of the debt issuance costs, respectively. The effective interest rate on the 2017 Notes was 8.0%, which includes the interest on the notes, amortization of the debt discount and debt issuance costs. Interest on the 2017 Notes began accruing upon issuance and was payable semi-annually. Concurrently, with the offering of the 2017 Notes the Company also entered into transactions for a convertible note hedge (the “2017 Hedge”) and warrants (the “2017 Warrants”). The 2017 Hedge entitled the Company to purchase up to 9,553,096 shares of the Company’s common stock at an initial price of $42.13 per share. effect of inclusion would always be anti-dilutive with respect to the calculation of diluted earnings per share. The 2017 Warrants entitled its holders 477,654 $988.51 20 Revolving Senior Credit Facility In April 2017, the Company entered into an Amended and Restated Credit Agreement (the “2017 Credit Agreement”) for a revolving senior credit facility (the “2017 Facility”), which replaced the previous Credit Agreement the Company had entered into in February 2016. The 2017 Credit Agreement provides for secured revolving loans, multicurrency loan options and letters of credit in an aggregate amount of up to $500.0 million. The 2017 Credit Agreement also contains an expansion feature, which allows the Company to increase the aggregate principal amount of the 2017 Facility provided the Company remains in compliance with the underlying financial covenants, including but not limited to, compliance with the consolidated interest coverage ratio and certain consolidated leverage ratios. The 2017 Facility matures in April 2022 (subject to an earlier springing maturity date), and includes a sublimit of $100.0 million for multicurrency borrowings, a sublimit of $50.0 million for the issuance of standby letters of credit, and a sublimit of $5.0 million for swingline loans. All assets of the Company and its material domestic subsidiaries are pledged as collateral under the 2017 Facility (subject to customary exceptions) pursuant to the term set forth in the Amended and Restated Security and Pledge Agreement (the “2017 Security Agreement”) executed in favor of the administrative agent by the Company. Each of the Company’s material domestic subsidiaries guarantees the 2017 Facility. In connection with the 2017 Facility, the Company incurred issuance costs which will be amortized over the term of the 2017 Facility. As of June 30, 2018, the Company had $37.0 million outstanding under the 2017 Facility, at an interest rate of 4.05% (one month LIBOR plus 1.75%). Borrowings under the 2017 Facility are used by the Company to provide financing for working capital and other general corporate purposes, including potential mergers and acquisitions. Borrowings under the 2017 Facility bear interest, at the Company’s option, at a rate equal to an applicable margin plus: (a) the applicable Eurocurrency Rate (as defined in the 2017 Credit Agreement), or (b) a base rate determined by reference to the highest of (1) the federal funds effective rate plus 0.50%, (2) the Bank of America prime rate, and (3) LIBOR for an interest period of one month plus 1.00%. The margin for the 2017 Facility ranges, based on the Company’s consolidated leverage ratio, from 0.00% to 1.00% in the case of base rate loans and from 1.00% to 2.00% in the case of Eurocurrency Rate loans. The 2017 Facility includes an unused line fee ranging, based on the Company’s consolidated leverage ratio, from 0.20% to 0.35% per annum on the revolving commitment. The 2017 Credit Agreement contains affirmative, negative, permitted acquisition and financial covenants, and events of default customary for financings of this type. The financial covenants require the Company to maintain ratios of consolidated earnings before interest, taxes, depreciation and amortization (EBITDA) in relation to consolidated interest expense and consolidated debt, respectively, as defined in the 2017 Credit Agreement. The 2017 Facility grants the lenders preferred first priority liens and security interests in capital stock, intercompany debt and all of the present and future property and assets of the Company and each guarantor. The Company is currently in compliance with the 2017 Credit Agreement covenants.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	7. Stock-Based Compensation The compensation cost that has been included in the Consolidated Statements of Operations for all stock-based compensation arrangements was as follows: Three Months Ended June 30, Six Months Ended June 30, ( in thousands 2018 2017 2018 2017 Sales, marketing and administrative expense $ 5,929 $ 7,891 $ 9,444 $ 14,686 Research and development expense 838 428 1,338 567 Cost of revenue 93 75 212 158 Stock-based compensation expense before taxes 6,860 8,394 10,994 15,411 Related income tax benefits (1,715 ) (3,190 ) (2,749 ) (5,856 ) Stock-based compensation expense, net of taxes $ 5,145 $ 5,204 $ 8,245 $ 9,555 At June 30, 2018, there was $53.9 million of unamortized compensation expense for restricted stock units (“RSUs”) and performance-based restricted stock units (“PRSUs”) to be recognized over a weighted average period of 2.3 years. Restricted Stock Units The Company issued approximately 38,000 and 150,000 shares of common stock, before net share settlement, upon vesting of RSUs (including PRSUs) during the three and six months ended June 30, 2018 and issued approximately 359,000 shares of common stock in settlement of RSUs (including PRSUs) upon their vesting during the year ended December 31, 2017. Stock Options and Purchase Rights The weighted average assumptions used to estimate the fair value of stock purchase rights under the employee stock purchase plan (“ESPP”) are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 ESPP Volatility 30 % 21 % 34 % 23 % Expected term (years) 0.5 0.5 0.5 0.5 Risk free interest rate 1.8 % 0.8 % 1.4 % 0.6 % Expected dividend yield — % — % — % — % Under the terms of the ESPP, the Company’s employees (referred to as “shareowners”) can elect to have up to 15% of their annual compensation, up to a maximum of $21,250 per year, withheld to purchase shares of the Company’s common stock for a purchase price equal to 85% of the lower of the fair market value per share (at closing) of the Company’s common stock on (i) the commencement date of the six-month offering period, or (ii) the respective purchase date. The Company has not granted any options since 2011. The Company issued approximately 43,000 and 103,000 shares of common stock, before net share settlement, upon the exercise of outstanding stock options during the three and six months ended June 30, 2018 and issued approximately 232,000 shares of common stock, before net share settlement, upon the exercise of outstanding stock options during the year ended December 31, 2017.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes Income taxes are determined using an estimated annual effective tax rate applied against income, and then adjusted for the tax impacts of certain significant and discrete items. For the six months ended June 30, 2018, the Company treated the tax impact of the following significant items as discrete events for which the tax effect was recognized separately from the application of the annual effective tax rate: tax expense related to net shortfalls on share-based payments, return to provision adjustments, favorable audit settlements, and limitations on certain officer’s compensation. The Company’s effective tax rate recorded for the six months ended June 30, 2018 was 25%. On December 22, 2017, President Trump signed U.S. tax reform legislation, commonly referred to as the Tax Cuts and Jobs Act (the “Act”), which became effective January 1, 2018. Due to insufficient guidance on certain aspects of the Act, such as officer’s compensation, as well as uncertainty around the GAAP treatment associated with many other parts of the Act, such as the implementation of certain international provisions, the Company recorded certain provisional amounts related to the revaluation and realization of its deferred taxes in its December 31, 2017 tax provision. During the six months ended June 30, 2018, the Company further analyzed the impact of the Act on certain executive compensation related deferred taxes as well as the federal tax rate revaluation impact on certain other existing deferred taxes and determined that an aggregate write-down of approximately $0.3 million was required, which would have increased the 2017 full year effective tax rate by 0.5% and the fourth quarter 2017 effective tax rate by 1.7%. The Company is continuing to analyze the impact of the Act during which adjustments to the 2017 year-end provisional calculation will be subject to change during the Staff Accounting Bulletin No. 118 measurement period. As the Company finalizes its analysis and adjusts its tax balances accordingly, it will describe the issue and impact on previously recorded provisional amounts. At June 30, 2018, the Company has not completed its accounting for the tax effects of the global intangible low-taxed income (“GILTI”), foreign derived intangible income (“FDII”), and base erosion and anti-abuse tax (“BEAT”) provisions of the Act on current year tax expense; however, the Company has made a reasonable estimate and determined that these provisions will have no impact on its 2018 results. Because the Company continues to evaluate the impact of the Act’s GILTI provisions, it has yet to elect an accounting policy to treat the tax impact as either a future period charge or as a current component of deferred taxes. In accordance with the disclosure requirements as described in ASC Topic 740, Income Taxes, the Company has classified unrecognized tax benefits as non-current income tax liabilities, or a reduction in deferred tax assets, unless expected to be paid within one year. The Company’s continuing practice is to recognize interest and/or penalties related to income tax matters in income tax expense. The Company had an increase in gross unrecognized tax benefits of approximately $0.9 million during the six months ended June 30, 2018, primarily related to research and development credits. The Company believes it is reasonably possible that approximately $6.5 million of its remaining unrecognized tax benefits may be recognized within the next twelve months as certain statute of limitations expire, the amount of which is primarily attributable to tax positions involving the valuation of intercompany transactions. In July 2018, the U.S. Ninth Circuit court of appeals overturned the U.S. Tax Court’s unanimous 2015 decision in Altera v. Commissioner The Company is subject to routine compliance reviews on various tax matters around the world in the ordinary course of business. Currently, income tax audits are being conducted with U.S. federal and Germany. U.S. states and most foreign jurisdictions remain subject to examination in all years due to prior year net operating losses and R&D credits.

Business Segment, Product, and

Business Segment, Product, and Geographic Information	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Business Segment, Product and Geographic Information	9. Business Segment, Product and Geographic Information The Company operates in one segment based upon the Company’s organizational structure, the way in which the operations and investments are managed and evaluated by the chief operating decision maker (“CODM”) as well as the lack of availability of discrete financial information at a lower level. The Company’s CODM reviews revenue at the product line offering level, and manufacturing, operating income and expenses, and net income at the Company wide level to allocate resources and assess the Company’s overall performance. The Company shares common, centralized support functions, including finance, human resources, legal, information technology, and corporate marketing, all of which report directly to the CODM. Accordingly, decision-making regarding the Company’s overall operating performance and allocation of Company resources is assessed on a consolidated basis. As such, the Company operates as one reporting segment. The Company has disclosed the revenues for each of its product line offerings to provide the reader of the financial statements transparency into the operations of the Company. The Company reports under two distinct product lines; spinal hardware and surgical support. The Company’s spinal hardware product line offerings include implants and fixation products. The Company’s surgical support product offerings include IOM services, disposables and biologics, all of which are used to aid spinal surgery. The Company has reclassified historically presented product line revenue to conform to the current period presentation. reclassification had no impact on previously reported results of operations Revenue by product line was as follows: Three Months Ended June 30, Six Months Ended June 30, ( in thousands 2018 2017 2018 2017 Spinal hardware $ 202,060 $ 184,725 $ 387,961 $ 359,812 Surgical support 79,504 74,674 154,125 148,600 Total revenue $ 281,564 $ 259,399 $ 542,086 $ 508,412 Revenue and property and equipment, net, by geographic area were as follows: Revenue Property and Equipment, Net Three Months Ended June 30, Six Months Ended June 30, June 30, December 31, ( in thousands 2018 2017 2018 2017 2018 2017 United States $ 226,949 $ 215,972 $ 440,252 $ 429,329 $ 195,980 $ 179,891 International (excludes Puerto Rico) 54,615 43,427 101,834 79,083 35,753 35,435 Total $ 281,564 $ 259,399 $ 542,086 $ 508,412 $ 231,733 $ 215,326

Commitments

Commitments	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments	10. Commitments Licensing and Purchasing Agreements As of June 30, 2018 the Company has obligations under certain consulting arrangements to pay up to approximately $47.2 million in the aggregate in the event that specified revenue-based milestones are achieved prior to 2027. Any such payment will be made in a combination of cash and the Company’s common shares as provided in the agreements. Any payments in satisfaction of these contingent obligations are considered either a research and development expense or a cost of revenue depending on the nature of the arrangement and are recognized ratably as and if milestones are achieved. These agreements expire on various dates through 2027. Executive Severance Plans The Company has employment contracts with key executives and maintains severance plans that provide for the payment of severance and other benefits if such executives are terminated for reasons other than cause, as defined in those agreements and plans. Certain agreements call for payments that are based on historical compensation, and accordingly, the amount of the contractual commitment will change over time commensurate with the executive’s earnings. At June 30, 2018, future commitments for such key executives were approximately $23.3 million. In certain circumstances, the agreements call for the acceleration of equity vesting. Those figures are not reflected in the above information.

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2018
Contingencies [Abstract]
Contingencies	11. Contingencies The Company is subject to potential liabilities under government regulations and various claims and legal actions that are pending or may be asserted from time-to-time. These matters arise in the ordinary course and conduct of the Company’s business and include, for example, commercial, intellectual property, environmental, securities and employment matters. The Company intends to continue to defend itself vigorously in such matters and when warranted, take legal action against others. Furthermore, the Company regularly assesses contingencies to determine the degree of probability and range of possible loss for potential accrual in its financial statements. During the three months ended June 30, 2018, the Company settled its ongoing litigation and related matters with Madsen Medical, Inc An estimated loss contingency is accrued in the Company’s financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Based on the Company’s assessment, it has adequately accrued an amount for contingent liabilities currently in existence. The Company does not accrue amounts for liabilities that it does not believe are probable or that it considers immaterial to its overall financial position. Litigation is inherently unpredictable, and unfavorable resolutions could occur. As a result, assessing contingencies is highly subjective and requires judgment about future events. The amount of ultimate loss may exceed the Company’s current accruals, and it is possible that its cash flows or results of operations could be materially affected in any particular period by the unfavorable resolution of one or more of these contingencies. Legal Proceedings Securities Litigation On August 28, 2013, a purported securities class action lawsuit was filed in the U.S. District Court for the Southern District of California naming the Company and certain of its current and former executive officers for allegedly making false and materially misleading statements regarding the Company’s business and financial results, specifically relating to the purported improper submission of false claims to Medicare and Medicaid. The operative complaint asserts a putative class period stemming from October 22, 2008 to July 30, 2013. The complaint alleges violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 promulgated thereunder and seeks unspecified monetary relief, interest, and attorneys’ fees. On February 13, 2014, Brad Mauss, the lead plaintiff in the case, filed an Amended Class Action Complaint for Violations of the Federal Securities Laws. The Company answered the complaint on August 25, 2016, and discovery commenced. The plaintiffs filed motions for class certification on October 28, 2016 and the Company’s opposition papers were filed on January 9, 2017. On March 22, 2017, the court issued an order granting class certification. The Company filed a petition to appeal the order granting class certification with the U.S. Court of Appeals for the Ninth Circuit (the “Ninth Circuit”) on April 5, 2017 and the plaintiffs filed an opposition to the petition. On August 15, 2017, the Ninth Circuit denied the Company’s petition. The Company filed a motion for summary judgment on September 8, 2017. On February 1, 2018, the court entered an order denying the Company’s motion for summary judgment. On February 13, 2018, the Company entered into a memorandum of understanding with the plaintiffs to settle the case for $7.9 million. On March 23, 2017, the parties executed a stipulation of settlement, which was preliminarily approved by the court on June 11, 2018. A hearing on the final approval of the settlement by the court has been scheduled for November 12, 2018. The Company expects the settlement will be fully funded by insurance proceeds. The settlement includes the dismissal of all claims against the Company and the named individuals in the lawsuit without any liability or wrongdoing attributed to them. There can be no assurance that a settlement will be finalized and approved or as to the ultimate outcome of this litigation. However, in connection with the proposed settlement and in accordance with authoritative guidance, the Company has recorded the loss contingency of $7.9 million as a current litigation liability and the expected insurance proceeds of $7.9 million as a current receivable in the Consolidated Balance Sheet as of June 30, 2018 and December 31, 2017. Madsen Medical, Inc. Litigation On February 19, 2016, an unfavorable jury verdict was delivered against the Company in its litigation in the U.S. District Court for the Southern District of California against Madsen Medical, Inc. (“MMI”), a former sales agent. Specifically, the jury awarded MMI $7.5 million in lost profits for tortious interference, $14.0 million for unjust enrichment, $20.0 million in punitive damages, and approximately $0.3 million in damages for breach of contract. he trial court entered judgment in favor of MMI in the amount of $27.8 million, which amount excluded the $14.0 million disgorgement awarded by the jury. On July 5, 2016, the trial court also awarded MMI attorney’s fees and costs of approximately $1.1 million. The Company’s post-trial motions for judgment as a matter of law and/or for a new trial were denied, and the Company appealed both the verdict and the court’s subsequent award of attorney’s fees and costs. The U.S. Court of Appeals for the Ninth Circuit held oral argument on April 12, 2018. During pendency of the appeal, the Company secured a bond to cover the amount of the judgment and attorneys’ fees and costs. As of December 31, 2017, the Company believed that the outcome of the case did not constitute a probable nor an estimable loss associated with the litigation, but rather a reasonably possible loss. The Company, based on its own assessment as well as that of outside counsel, believed that it was probable upon appeal the judgment would be vacated. Accordingly, the Company did not record a loss contingency at December 31, 2017, but assessed a reasonable range of potential loss, which would be from zero to the current amount entered as a judgment, as well as attorney’s fees and interest. Following the April 12, 2018 oral argument, the Company believed that the prior judgments against it, in part or as a whole, may be upheld. Accordingly, at March 31, 2018, the Company believed that the outcome of the case constituted a probable loss. While the actual amount of the probable loss was not known, the Company assessed a range of potential loss in accordance with Accounting Standards Codification 450, Contingencies, which would be from zero to $29.0 million, and recorded an additional estimated loss contingency in the amount of $29.0 million as a current litigation liability in the Unaudited Consolidated Balance Sheet as of March 31, 2018, resulting in an aggregate litigation liability of $29.0 million accrued for this matter. In May 2018, the Company entered into an agreement to settle all outstanding matters with MMI for $27.8 million. As a result of the settlement, the Company adjusted its litigation liability from $29.0 million to $27.8 million, which resulted in a $1.2 million gain which was recorded in the Consolidated Statement of Operations during the three months ended June 30, 2018. The Company has paid the settlement amount and no longer has any remaining liability related to this matter as of June 30, 2018.

Regulatory Matters

Regulatory Matters	6 Months Ended
	Jun. 30, 2018
Regulatory Matter [Abstract]
Regulatory Matters	12. Regulatory Matters On August 31, 2015, the Company received a civil investigative demand (“CID”) issued by the Department of Justice (“DOJ”) pursuant to the federal False Claims Act. The CID requires the delivery of a wide range of documents and information related to an investigation by the DOJ concerning allegations that the Company assisted a physician group customer in submitting improper claims for reimbursement and made improper payments to the physician group in violation of the Anti-Kickback Statute. The Company is cooperating with the DOJ. No assurance can be given as to the timing or outcome of this investigation. At June 30, 2018, the probable outcome of this matter cannot be determined, nor can the Company estimate a range of potential loss. In accordance with authoritative guidance on the evaluation of loss contingencies, the Company has not recorded an accrual related to this matter. On June 9, 2017, the Company received a subpoena from the Office of the Inspector General of the U.S. Department of Health and Human Services (“OIG”) in connection with an investigation into possible false or otherwise improper claims submitted to Medicare and Medicaid. The subpoena seeks discovery of documents for the period January 2014 through June 2017, primarily associated with sales to a particular customer and relationships related to that customer account. The Company is working with the OIG to understand the scope of the subpoena and its request for documents, and the Company intends to fully cooperate with the OIG's request. No assurance can be given as to the timing or outcome of this investigation. At June 30, 2018, the probable outcome of this matter cannot be determined, nor can the Company estimate a range of potential loss. In accordance with authoritative guidance on the evaluation of loss contingencies, the Company has not recorded an accrual related to this matter.

Description of Business and B20

Description of Business and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	Description of Business NuVasive, Inc. (the “Company” or “NuVasive”) was incorporated in Delaware on July 21, 1997, and began commercializing its products in 2001. The Company’s principal product offering includes a minimally-disruptive surgical platform called Maximum Access Surgery, or MAS. The MAS platform combines three categories of solutions that collectively minimize soft tissue disruption during spine fusion surgery, provide maximum visualization and are designed to enable safe and reproducible outcomes for the surgeon and the patient. The platform includes the Company’s proprietary software-driven nerve detection and avoidance systems and Intraoperative Monitoring (“IOM”) services and support; MaXcess, an integrated split-blade retractor system; and a wide variety of specialized implants and biologics. To assist with surgical procedures the Company offers a technology platform called Integrated Global Alignment (“iGA”); in which products and computer assisted technology under the MAS platform help achieve more precise spinal alignment. The individual components of the MAS platform, and many of the Company’s products, can also be used in open or traditional spine surgery. The Company continues to focus research and development efforts to expand its MAS product platform and advance the applications of its unique technology into procedurally-integrated surgical solutions. The Company dedicates significant resources toward training spine surgeons on its unique technology and products. The Company’s procedurally integrated solutions use innovative, technological advancements and the MAS platform to provide surgical efficiency, operative reliability, and procedural versatility. The Company offers a range of implants for spinal surgery, which include its branded CoRoent products and porous titanium and polyetheretherketone implants under its Advanced Materials Science portfolio, fixation devices such as customizable rods, plates and screws, bone allograft in patented saline packaging, allogeneic and synthetic biologics, and disposables used in IOM. The Company makes available MAS instrument sets, MaXcess and neuromonitoring systems to hospitals to facilitate surgeon access to the spine to perform restorative and fusion procedures using the Company’s implants and fixation devices. The Company sells MAS instrument sets, MaXcess and neuromonitoring systems to hospitals, however, such sales are immaterial to the Company’s results of operations. The Company also designs and sells expandable growing rod implant systems that can be non-invasively lengthened following implantation with precise, incremental adjustments via an external remote controller using magnetic technology called MAGnetic External Control, or MAGEC, which allows for the minimally invasive treatment of early-onset and adolescent scoliosis. This technology is also the basis for the Company’s PRECICE limb lengthening system, which allows for the correction of long bone limb length discrepancy, as well as enhanced bone healing in patients that have experienced traumatic injury. The Company intends to continue development on a wide variety of projects intended to broaden surgical applications for greater procedural integration of its MAS techniques and additional applications of the MAGEC technology. Such applications include tumor, trauma, and deformity, as well as increased fixation options, sagittal alignment products, imaging and navigation. The Company also expects to continue expanding its other product and services offerings as it executes on its strategy to offer customers an end-to-end, procedurally integrated solution for spine surgery. The Company intends to continue to pursue business and technology acquisition targets and strategic partnerships.
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying Unaudited Consolidated Financial Statements include the accounts of the Company and its majority-owned or controlled subsidiaries, collectively referred to as either NuVasive or the Company. The Company translates the financial statements of its foreign subsidiaries using end-of-period exchange rates for assets and liabilities and average exchange rates during each reporting period for results of operations. When there is a portion of equity in an acquired subsidiary not attributable, directly or indirectly, to the respective parent entity, the Company records the fair value of the non-controlling interest at the acquisition date and classifies the amounts attributable to non-controlling interest separately in equity in the Company's Consolidated Financial Statements. Any subsequent changes in a parent's ownership interest while the parent retains its controlling financial interest in its subsidiary are accounted for as equity transactions. All significant intercompany balances and transactions have been eliminated in consolidation. The accompanying Unaudited Consolidated Financial Statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Pursuant to these rules and regulations, the Company has condensed or omitted certain information and footnote disclosures it normally includes in its annual Consolidated Financial Statements prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). Operating results for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for any other interim period or for the full year. These Unaudited Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and notes thereto for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC. In the opinion of management, the Unaudited Consolidated Financial Statements and notes thereto include all adjustments that are of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position and of the results of operations and cash flows for the periods presented. The Company has reclassified historically presented revenue and cost of revenue to conform to the current year presentation, which now reflects revenue and costs allocated to the Company’s product and service offerings. T Revenue from Contracts with Customers (“ASU 2014-09”) on January 1, 2018 adopted Accounting Standards Codification 606 Revenue from Contracts with Customers (“ASC 606”), electing full retrospective method of adoption.
Use of Estimates	Use of Estimates To prepare financial statements in conformity with GAAP, management must make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Recently Accounting Pronouncements Not Yet Adopted And Recently Adopted Accounting Standards	Recent Accounting Pronouncements Not Yet Adopted In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2016-02, Leases, which introduced ASC 842 – Leases, a new comprehensive lease accounting model that supersedes the current lease guidance under ASC 840 – Leases . The new accounting standard requires lessees to recognize right-of-use assets and corresponding lease liabilities for all leases with lease terms of greater than twelve months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. The new accounting standard must be adopted using the modified retrospective approach and will be effective for the Company starting in the first quarter of fiscal 2019. Early adoption is permitted. The Company is in the process of determining the impact the adoption will have on its Consolidated Financial Statements and expects significant changes relating to the recognition of right-of-use assets and liabilities associated with its operating leases. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments – Credit Losses The Company believes the adoption will modify the way the Company analyzes financial instruments, but it does not anticipate a material impact on results of operations. In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles – Goodwill and Other In July 2017, the FASB issued Accounting Standards Update No. 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity, Derivatives and Hedging early adoption is permitted. In August 2017, the FASB issued Accounting Standards Update No. 2017-12, Derivatives and Hedging In March 2018, the FASB issued Accounting Standards Update No. 2018-05, Income taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 In June 2018, the FASB issued Accounting Standards Update No. 2018-07, Compensation – Stock Compensation Recently Adopted Accounting Standards In May 2014, the FASB issued Accounting Standard Update No. 2014-09 Revenue from Contracts with Customers Prior to the adoption of ASC 606, the Company recognized revenue in accordance with ASC 605 when all four of the following criteria were met: (i) persuasive evidence that an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the selling price is fixed or determinable; and (iv) collectability is reasonably assured. Specifically, revenue from the sale of implants, biologics and disposables was generally recognized upon a purchase order from the hospital or acknowledgment from the hospital indicating product use or implantation or upon shipment to third-party customers who immediately accepted title. Revenue from the sale of instrument sets was recognized upon receipt of a purchase order and the subsequent shipment to customers who immediately accepted title. Revenue from neuromonitoring services was recognized in the period the service was performed for the amount of payment expected to be received. The Company adopted ASC 606 as of January 1, 2018, electing full retrospective method of adoption, which resulted in a change in its accounting policy for revenue recognition and related adjustments to the Consolidated Financial Statements for all periods presented. The Company applied the practical expedients permitted under ASC 606 for which (i) contracts with customers originating prior to January 1, 2016 do not require disclosure for the amount of consideration allocated to remaining performance obligations or an explanation of when the Company expects to recognize that amount as revenue; (ii) contracts beginning and completing in the same annual reporting period need not be restated; and (iii) hindsight for estimating variable consideration for completed contracts is permitted. The Company recognizes revenue from spinal surgery hardware and ancillary products at a point in time in two types of transactions: (i) procedural based transactions with products used during surgery defined as “charge sheet orders”, and (ii) shipping transactions which represent the stocking of product or the purchase of instrumentation to support future surgeries defined as “stocking and capital orders”. The Company also recognizes revenue at a point in time associated with surgical-related servicing procedures, including neuromonitoring services which are defined as “surgical-related services”. Other sources of revenue, such as leasing revenue and royalties, are immaterial to the Consolidated Financial Statements. For charge sheet orders, the sale occurs when the surgery is performed and a charge sheet is submitted to the Company by its sales representative identifying the products consumed during the surgery. The charge sheet, as signed by the hospital, serves as a confirmation and acknowledgement of the Company’s products consumed during a surgery. Under ASC 605, persuasive evidence of an arrangement and delivery of product was deemed to have occurred once the charge sheet was processed, and an associated authorization or acknowledgement from the customer was received. Under ASC 606, the Company’s charge sheet orders are considered to be a contract with a customer when a surgery is scheduled with the Company as requested by the hospital or surgeon, and the products are consumed during the surgery or implanted into the patient. Revenue recognition under ASC 606 occurs upon completion of the Company’s performance obligation, which occurs upon consumption of the products during surgery and receipt of the charge sheet. In the event that information related to the surgical event and consumption of product is not readily available the Company recognizes revenue upon a purchase order from the hospital or acknowledgment from the hospital indicating product use. For stocking and capital orders, under ASC 605, delivery was deemed to have occurred when the title, including all risks and rewards of ownership of the products specified in the sales agreement had passed to the buyer. Accordingly, title, including all risks and rewards of ownership, passed based on the shipping terms. Under ASC 606, the Company’s stocking and capital order performance obligation is considered to be satisfied when the hospital assumes control of the asset, either upon shipment or delivery depending on the terms, and ability to direct the use of the asset as appropriate without the Company’s consent. Under both ASC 605 and ASC 606, revenue from surgical-related services, such as neuromonitoring services, is recognized in the period the service is performed based on the delivery of a services report to the customer. The Company recognizes revenue for the amount of payment expected to be received. The Company bills either hospitals or insurance companies for different aspects of the service, as applicable. Revenue from hospitals is recognized based on agreed upon pricing. Revenue from insurance companies is recognized using the expected value method, as the Company bills at a gross rate which is generally not the rate ultimately collected. Under ASC 605, the Company has historically estimated the amounts of returns, trade-ins, discounts, rebates, credits or incentives as offsets to the total transaction price or revenue associated with the sale. In limited situations, when historical information was not available or reliable, the Company would defer revenue recognition until completion of all performance obligations. Under ASC 606, the Company analyzes sales that could include variable consideration, and estimates the expected or most likely amount of revenue after returns, trade-ins, discounts, rebates, credits, and incentives. In making these estimates, the Company considers whether the amount of variable consideration is constrained and is included in revenue only to the extent that it is probable that a significant reversal of the revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company earns sales-based royalty revenue over time from sales of products using existing biologics intellectual property (“IP”) that is out-licensed to certain companies. Under ASC 605, royalty revenue was recognized as earned and when collection was reasonably assured and was generally estimated and recorded in the same period as the sales that generated the royalty obligation. ASC 606 provides an exception for sales or usage-based royalties from the guidance for accounting for variable consideration, allowing the royalty revenue from the license of IP to be recognized when the performance obligation has been satisfied and the subsequent sale has occurred. Therefore, the Company estimates monthly royalty revenue as its performance obligation is satisfied. The Company does not expect a significant impact to royalty revenue under the adoption of ASC 606 as it has historically estimated and accrued royalty revenue in the period earned. The Company historically expensed incremental costs, such as commissions associated with sales contracts, as incurred. Under ASU 2014-09, ASC 340-40 Other Assets and Deferred Costs was added along with ASC 606 to codify accounting guidance for the incremental costs to obtain or fulfill a contract with a customer. Under the guidance, the incremental costs must be deferred and recorded over the period in which the contract revenue is recognized. The Company typically does not associate quarterly or annual sales bonuses directly with a sale or master contract; however, commissions are directly associated with individual sales and expensed in the same period as the related contract revenue. The associated commissionable sales would not typically have a future benefit unless the revenue is recognized over time. The Company does not typically have situations where revenue is deferred in excess of one year. Given the practical expedient for contracts completing within one year, the Company does not expect these capitalized costs to be material in a given period. The cumulative effect of the change on retained earnings for the full retrospective method of adoption of ASC 606 was $0.3 million as of December 31, 2017. NUVASIVE, INC. CONSOLIDATED BALANCE SHEET (in thousands) (Unaudited) (Unaudited) As of December 31, 2017 As reported Adjustments As Adjusted Accounts receivable, gross $ 212,709 $ 537 [a] $ 213,246 Allowances on accounts receivable (13,669 ) 643 [b] (13,026 ) Inventory, net 247,245 (107 ) [c] 247,138 Other current assets 112,705 — 112,705 Total current assets 558,990 1,073 560,063 Remaining other assets 1,080,077 — 1,080,077 Total assets $ 1,639,067 $ 1,073 $ 1,640,140 Accounts payable and accrued liabilities 75,076 691 [d] 75,767 Accrued payroll and related expenses 55,582 36 [e] 55,618 Other current liabilities 30,010 — 30,010 Total current liabilities 160,668 727 161,395 Deferred and income tax liabilities, non-current 18,786 84 [f] 18,870 Other long-term liabilities 660,459 — 660,459 Total NuVasive, Inc. stockholders’ equity 795,309 262 [g] 795,571 Non-controlling interests 3,845 — 3,845 Total equity 799,154 262 799,416 Total liabilities and equity $ 1,639,067 $ 1,073 $ 1,640,140 [a] Represents cumulative impact from January 1, 2016 to the period presented on accounts receivable for the full retrospective method of adoption of ASC 606. [b] Represents cumulative impact from January 1, 2016 to the period presented on allowances on accounts receivable for the full retrospective method of adoption of ASC 606. [c] Represents cumulative impact from January 1, 2016 to the period presented on inventory for the full retrospective method of adoption of ASC 606. [d] Represents cumulative impact from January 1, 2016 to the period presented on commissions payable and accrued returns for the full retrospective method of adoption of ASC 606. [e] Represents cumulative impact from January 1, 2016 to the period presented on commissions payable for the full retrospective method of adoption of ASC 606. [f] Represents cumulative impact from January 1, 2016 to the period presented on deferred tax liabilities for the full retrospective method of adoption of ASC 606. [g] Represents cumulative impact from January 1, 2016 to the period presented on retained earnings for the full retrospective method of adoption of ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (in thousands, except per share amounts) (Unaudited) As reported Adjustments As adjusted Three months ended June 30, 2017 Revenue Product revenue $ 238,998 $ (1,174 ) [a] $ 237,824 Service revenue 21,575 — 21,575 Total revenue 260,573 (1,174 ) 259,399 Cost of revenue (excluding amortization of intangible assets) Cost of products sold 50,770 (235 ) [b] 50,535 Cost of services 15,651 — 15,651 Total cost of revenue 66,421 (235 ) 66,186 Gross profit 194,152 (939 ) 193,213 Operating expenses: Sales, marketing and administrative 139,109 (142 ) [c] 138,967 Other operating expenses 25,290 — 25,290 Total operating expenses 164,399 (142 ) 164,257 Total interest and other expense, net (10,445 ) — (10,445 ) Income tax (expense) benefit (7,079 ) 303 [d] (6,776 ) Consolidated net income $ 12,229 $ (494 ) [e] $ 11,735 Add back net loss attributable to non-controlling interests $ (432 ) $ — $ (432 ) Net income attributable to NuVasive, Inc. $ 12,661 $ (494 ) [e] $ 12,167 Net income per share attributable to NuVasive, Inc.: Basic $ 0.25 $ (0.01 ) [f] $ 0.24 Diluted $ 0.22 $ (0.01 ) [f] $ 0.21 Comprehensive income attributable to NuVasive, Inc. $ 13,304 $ (494 ) [e] $ 12,810 [a] Represents net change in sales revenue for charge sheet orders recognized under ASC 606. [b] Represents net change in cost of products sold for charge sheet orders recognized under ASC 606. [c] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. [d] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [e] Represents change in net income and comprehensive income resulting from net change in charge sheet orders recognized under ASC 606. [f] Represents earnings per share impact resulting from net change in charge sheet orders recognized under ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (in thousands, except per share amounts) (Unaudited) As reported Adjustments As adjusted Six months ended June 30, 2017 Revenue Product revenue $ 464,804 $ (2,025 ) [a] $ 462,779 Service revenue 45,633 — 45,633 Total revenue 510,437 (2,025 ) 508,412 Cost of revenue (excluding amortization of intangible assets) Cost of products sold 96,841 (405 ) [b] 96,436 Cost of services 31,193 — 31,193 Total cost of revenue 128,034 (405 ) 127,629 Gross profit 382,403 (1,620 ) 380,783 Operating expenses: Sales, marketing and administrative 279,611 (276 ) [c] 279,335 Other operating expenses 49,820 — 49,820 Total operating expenses 329,431 (276 ) 329,155 Total interest and other expense, net (19,849 ) — (19,849 ) Income tax (expense) benefit (8,569 ) 508 [d] (8,061 ) Consolidated net income $ 24,554 $ (836 ) [e] $ 23,718 Add back net loss attributable to non-controlling interests $ (875 ) $ — $ (875 ) Net income attributable to NuVasive, Inc. $ 25,429 $ (836 ) [e] $ 24,593 Net income per share attributable to NuVasive, Inc.: Basic $ 0.50 $ (0.02 ) [f] $ 0.48 Diluted $ 0.44 $ (0.01 ) [f] $ 0.42 Comprehensive income attributable to NuVasive, Inc. $ 27,929 $ (836 ) [e] $ 27,093 [a] Represents net change in sales revenue for charge sheet orders recognized under ASC 606. [b] Represents net change in cost of products sold for charge sheet orders recognized under ASC 606. [c] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. [d] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [e] Represents change in net income and comprehensive income resulting from net change in charge sheet orders recognized under ASC 606. [f] Represents earnings per share impact resulting from net change in charge sheet orders recognized under ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF CASH FLOWS (in thousands) (Unaudited) Six months ended June 30, 2017 As reported Adjustments As adjusted Consolidated net income $ 24,554 $ (836 ) [a] $ 23,718 Adjustments to reconcile net income to net cash provided by operating activities: Reserves on current assets (95 ) 159 [b] 64 Deferred income tax benefit (2,570 ) (507 ) [c] (3,077 ) Other adjustments to reconcile net income 92,361 — 92,361 Changes in operating assets and liabilities, net of effects from acquisitions: Accounts receivable (17,586 ) 1,763 [d] (15,823 ) Inventory (29,012 ) (405 ) [e] (29,417 ) Prepaid expenses and other current assets (2,543 ) — (2,543 ) Accounts payable and accrued liabilities 4,987 (119 ) [f] 4,868 Litigation liability (11,200 ) — (11,200 ) Accrued payroll and related expenses (2,004 ) (55 ) [f] (2,059 ) Income taxes 10,172 — 10,172 Net cash provided by operating activities 67,064 — 67,064 Net cash used in investing activities (84,802 ) — (84,802 ) Net cash used in financing activities (6,480 ) — (6,480 ) Effect of exchange rate changes on cash 1,449 — 1,449 Decrease in cash, cash equivalents and restricted cash $ (22,769 ) $ — $ (22,769 ) [a] Represents change in net income resulting from charge sheet orders recognized under ASC 606. [b] Represents net change in allowances on accounts receivable for charge sheet orders recognized under ASC 606. [c] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [d] Represents net change in accounts receivable for charge sheet orders recognized under ASC 606. [e] Represents net change in inventory for charge sheet orders recognized under ASC 606. [f] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. In January 2016, the FASB issued Accounting Standards Update No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities provides a practicability exception for investments that do not have readily determinable fair values, practicability exception for measuring equity investments that do not have readily determinable fair market In August 2016, the FASB issued Accounting Standards Update No. 2016-15, Classification of Certain Cash Receipts and Cash Payments In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Restricted Cash In January 2017, the FASB issued Accounting Standards Update No. 2017-01, Clarifying the Definition of a Business In February 2017, the FASB issued Accounting Standards Update No. 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets In May 2017, the FASB issued Accounting Standards Update No. 2017-09, Compensation – Stock Compensation
Revenue Recognition	Revenue Recognition In accordance with ASC 606 guidance, the Company recognizes revenue upon the transfer of goods or services to a customer at an amount that reflects the expected consideration to be received in exchange for those goods or services. The principles in ASC 606 are applied using the following five steps: dentify the contract with a customer dentify the performance obligation(s) in the contract etermine the transaction price llocate the transaction price to the performance obligation(s) in the contract; ecognize revenue when (or as) the Company satisfies its performance obligation(s) Revenue from neuromonitoring services is recognized in the period the service is performed for the amount of consideration expected to be received. In certain cases, the Company does offer the ability for customers to lease instrumentation primarily on a non-sales type basis. Revenue associated with products holding rights of return or trade-in are recognized when the Company concludes there is not a risk of significant revenue reversal in future periods for the expected consideration in the transaction. Costs incurred by the Company associated with sales contracts with customers are deferred over the performance obligation period and recognized in the same period as the related revenue, with the exception of contracts that complete within one year or less, in which case the associated costs are expensed as incurred.
Inventory	Inventory Net inventory as of June 30, 2018 primarily consisted of $244.4 million of finished goods, $10.2 million of work in progress and $5.2 million of raw materials. Net inventory as of December 31, 2017 consisted of $232.4 million of finished goods, $9.8 million of work in progress and $5.0 million of raw materials. Finished goods include specialized implants and disposables and are stated at the lower of cost or market determined by utilizing a standard cost method, which includes assessment of capitalized variances, which approximates the weighted average cost. Work in progress and raw materials represent the underlying material, and labor for work in progress, that ultimately yield finished goods upon completion and are subject to lower of cost or market. The Company reviews the components of its inventory on a periodic basis for excess and obsolescence and adjusts inventory to its net realizable value as necessary.
Comprehensive Income	Comprehensive Income Comprehensive income is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive income includes net of tax, unrealized gains or losses on the Company’s marketable securities and foreign currency translation adjustments. The cumulative translation adjustments included in accumulated other comprehensive loss were $8.9 million and $6.9 million at June 30, 2018 and December 31, 2017, respectively.
Product Shipment Costs	Product Shipment Costs Product shipment costs, included in sales, marketing and administrative expense in the accompanying Consolidated Statements of Operations, were $6.4 million and $12.3 million for the three and six months ended June 30, 2018, respectively, and $5.7 million and $11.6 million for the three and six months ended June 30, 2017, respectively. The majority of the Company’s shipping costs are related to the loaning of instrument sets, which are not typically sold as part of the Company’s core sales offering. Amounts billed to customers for shipping and handling of products are reflected in revenues and are not material for any period presented .
Business Transition Costs	Business Transition Costs The Company incurs certain costs related to acquisition, integration and business transition activities, which include severance, relocation, consulting, leasehold exit costs, third-party merger and acquisition costs, contingent consideration fair value adjustments and other costs directly associated with such activities. The Company incurred $4.0 million and $6.3 million of such costs during the three and six months ended June 30, 2018, respectively, which consisted primarily of acquisition, integration and business transition activities, but also includes $0.6 million and $0.8 million, respectively, of fair value adjustments on contingent consideration liabilities associated with the Company’s 2017 and 2016 acquisitions. During both the three and six months ended June 30, 2017, the Company incurred $1.4 million of such costs, which included $0.7 million and $(0.7) million, respectively, of fair value adjustments on contingent consideration liabilities associated with the Company’s 2017 and 2016 acquisitions, and other costs related to acquisition, integration and business transition activities.

Description of Business and B21

Description of Business and Basis of Presentation (Tables)	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Impacts of ASC 606 Adoption on the Company's Previously Filed Unaudited Consolidated Financial Statements	The following tables summarize in a condensed presentation the impact of the adoption of ASC 606 on the Company’s previously reported Consolidated Balance Sheet as of December 31, 2017, the Unaudited Consolidated Statement of Operations and Comprehensive Income for the three and six months ended June 30, 2017, and the Unaudited Consolidated Statement of Cash Flows for the six months ended June 30, 2017. NUVASIVE, INC. CONSOLIDATED BALANCE SHEET (in thousands) (Unaudited) (Unaudited) As of December 31, 2017 As reported Adjustments As Adjusted Accounts receivable, gross $ 212,709 $ 537 [a] $ 213,246 Allowances on accounts receivable (13,669 ) 643 [b] (13,026 ) Inventory, net 247,245 (107 ) [c] 247,138 Other current assets 112,705 — 112,705 Total current assets 558,990 1,073 560,063 Remaining other assets 1,080,077 — 1,080,077 Total assets $ 1,639,067 $ 1,073 $ 1,640,140 Accounts payable and accrued liabilities 75,076 691 [d] 75,767 Accrued payroll and related expenses 55,582 36 [e] 55,618 Other current liabilities 30,010 — 30,010 Total current liabilities 160,668 727 161,395 Deferred and income tax liabilities, non-current 18,786 84 [f] 18,870 Other long-term liabilities 660,459 — 660,459 Total NuVasive, Inc. stockholders’ equity 795,309 262 [g] 795,571 Non-controlling interests 3,845 — 3,845 Total equity 799,154 262 799,416 Total liabilities and equity $ 1,639,067 $ 1,073 $ 1,640,140 [a] Represents cumulative impact from January 1, 2016 to the period presented on accounts receivable for the full retrospective method of adoption of ASC 606. [b] Represents cumulative impact from January 1, 2016 to the period presented on allowances on accounts receivable for the full retrospective method of adoption of ASC 606. [c] Represents cumulative impact from January 1, 2016 to the period presented on inventory for the full retrospective method of adoption of ASC 606. [d] Represents cumulative impact from January 1, 2016 to the period presented on commissions payable and accrued returns for the full retrospective method of adoption of ASC 606. [e] Represents cumulative impact from January 1, 2016 to the period presented on commissions payable for the full retrospective method of adoption of ASC 606. [f] Represents cumulative impact from January 1, 2016 to the period presented on deferred tax liabilities for the full retrospective method of adoption of ASC 606. [g] Represents cumulative impact from January 1, 2016 to the period presented on retained earnings for the full retrospective method of adoption of ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (in thousands, except per share amounts) (Unaudited) As reported Adjustments As adjusted Three months ended June 30, 2017 Revenue Product revenue $ 238,998 $ (1,174 ) [a] $ 237,824 Service revenue 21,575 — 21,575 Total revenue 260,573 (1,174 ) 259,399 Cost of revenue (excluding amortization of intangible assets) Cost of products sold 50,770 (235 ) [b] 50,535 Cost of services 15,651 — 15,651 Total cost of revenue 66,421 (235 ) 66,186 Gross profit 194,152 (939 ) 193,213 Operating expenses: Sales, marketing and administrative 139,109 (142 ) [c] 138,967 Other operating expenses 25,290 — 25,290 Total operating expenses 164,399 (142 ) 164,257 Total interest and other expense, net (10,445 ) — (10,445 ) Income tax (expense) benefit (7,079 ) 303 [d] (6,776 ) Consolidated net income $ 12,229 $ (494 ) [e] $ 11,735 Add back net loss attributable to non-controlling interests $ (432 ) $ — $ (432 ) Net income attributable to NuVasive, Inc. $ 12,661 $ (494 ) [e] $ 12,167 Net income per share attributable to NuVasive, Inc.: Basic $ 0.25 $ (0.01 ) [f] $ 0.24 Diluted $ 0.22 $ (0.01 ) [f] $ 0.21 Comprehensive income attributable to NuVasive, Inc. $ 13,304 $ (494 ) [e] $ 12,810 [a] Represents net change in sales revenue for charge sheet orders recognized under ASC 606. [b] Represents net change in cost of products sold for charge sheet orders recognized under ASC 606. [c] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. [d] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [e] Represents change in net income and comprehensive income resulting from net change in charge sheet orders recognized under ASC 606. [f] Represents earnings per share impact resulting from net change in charge sheet orders recognized under ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (in thousands, except per share amounts) (Unaudited) As reported Adjustments As adjusted Six months ended June 30, 2017 Revenue Product revenue $ 464,804 $ (2,025 ) [a] $ 462,779 Service revenue 45,633 — 45,633 Total revenue 510,437 (2,025 ) 508,412 Cost of revenue (excluding amortization of intangible assets) Cost of products sold 96,841 (405 ) [b] 96,436 Cost of services 31,193 — 31,193 Total cost of revenue 128,034 (405 ) 127,629 Gross profit 382,403 (1,620 ) 380,783 Operating expenses: Sales, marketing and administrative 279,611 (276 ) [c] 279,335 Other operating expenses 49,820 — 49,820 Total operating expenses 329,431 (276 ) 329,155 Total interest and other expense, net (19,849 ) — (19,849 ) Income tax (expense) benefit (8,569 ) 508 [d] (8,061 ) Consolidated net income $ 24,554 $ (836 ) [e] $ 23,718 Add back net loss attributable to non-controlling interests $ (875 ) $ — $ (875 ) Net income attributable to NuVasive, Inc. $ 25,429 $ (836 ) [e] $ 24,593 Net income per share attributable to NuVasive, Inc.: Basic $ 0.50 $ (0.02 ) [f] $ 0.48 Diluted $ 0.44 $ (0.01 ) [f] $ 0.42 Comprehensive income attributable to NuVasive, Inc. $ 27,929 $ (836 ) [e] $ 27,093 [a] Represents net change in sales revenue for charge sheet orders recognized under ASC 606. [b] Represents net change in cost of products sold for charge sheet orders recognized under ASC 606. [c] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606. [d] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [e] Represents change in net income and comprehensive income resulting from net change in charge sheet orders recognized under ASC 606. [f] Represents earnings per share impact resulting from net change in charge sheet orders recognized under ASC 606. NUVASIVE, INC. CONSOLIDATED STATEMENT OF CASH FLOWS (in thousands) (Unaudited) Six months ended June 30, 2017 As reported Adjustments As adjusted Consolidated net income $ 24,554 $ (836 ) [a] $ 23,718 Adjustments to reconcile net income to net cash provided by operating activities: Reserves on current assets (95 ) 159 [b] 64 Deferred income tax benefit (2,570 ) (507 ) [c] (3,077 ) Other adjustments to reconcile net income 92,361 — 92,361 Changes in operating assets and liabilities, net of effects from acquisitions: Accounts receivable (17,586 ) 1,763 [d] (15,823 ) Inventory (29,012 ) (405 ) [e] (29,417 ) Prepaid expenses and other current assets (2,543 ) — (2,543 ) Accounts payable and accrued liabilities 4,987 (119 ) [f] 4,868 Litigation liability (11,200 ) — (11,200 ) Accrued payroll and related expenses (2,004 ) (55 ) [f] (2,059 ) Income taxes 10,172 — 10,172 Net cash provided by operating activities 67,064 — 67,064 Net cash used in investing activities (84,802 ) — (84,802 ) Net cash used in financing activities (6,480 ) — (6,480 ) Effect of exchange rate changes on cash 1,449 — 1,449 Decrease in cash, cash equivalents and restricted cash $ (22,769 ) $ — $ (22,769 ) [a] Represents change in net income resulting from charge sheet orders recognized under ASC 606. [b] Represents net change in allowances on accounts receivable for charge sheet orders recognized under ASC 606. [c] Represents deferred income tax liability on net change associated with charge sheet orders recognized under ASC 606. [d] Represents net change in accounts receivable for charge sheet orders recognized under ASC 606. [e] Represents net change in inventory for charge sheet orders recognized under ASC 606. [f] Represents net change in accrued sales commissions for charge sheet orders recognized under ASC 606.

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Income (Loss) Per Share	The following table sets forth the computation of basic and diluted net income (loss) per share attributable to the Company: Three Months Ended June 30, Six Months Ended June 30, ( in thousands, except per share data 2018 2017 2018 2017 Numerator: Net income (loss) attributable to NuVasive, Inc. $ 11,531 $ 12,167 $ (15,601 ) $ 24,593 Denominator for basic and diluted net income (loss) per share: Weighted average common shares outstanding for basic 51,356 51,082 51,292 50,825 Dilutive potential common stock outstanding: Stock options and employee stock purchase plan 30 138 — 180 Restricted stock units 570 1,356 — 1,386 Warrants — 2,929 — 2,987 Senior Convertible Notes — 2,825 — 2,681 Weighted average common shares outstanding for diluted 51,956 58,330 51,292 58,059 Basic net income (loss) per share attributable to NuVasive, Inc. $ 0.22 $ 0.24 $ (0.30 ) $ 0.48 Diluted net income (loss) per share attributable to NuVasive, Inc. $ 0.22 $ 0.21 $ (0.30 ) $ 0.42
Anti-dilutive Common Stock Equivalents Not Included in Calculation of Net Income (Loss) Per Diluted Share	The following weighted-average outstanding common stock equivalents were not included in the calculation of net income (loss) per diluted share because their effects were anti-dilutive: Three Months Ended June 30, Six Months Ended June 30, ( in thousands 2018 2017 2018 2017 Stock options, employee stock purchase plan, and restricted stock units 161 41 1,281 71 Warrants 10,865 10,865 10,865 10,865 Senior Convertible Notes 10,865 — 10,865 — Total 21,891 10,906 23,011 10,936

Financial Instruments and Fai23

Financial Instruments and Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis	Cash equivalents are determined under the fair value categories as follows: Quoted Price in Significant Other Significant Active Market Observable Inputs Unobservable ( in thousands Total (Level 1) (Level 2) Inputs (Level 3) June 30, 2018: Cash equivalents: Money market funds $ 20,000 $ 20,000 $ — $ — Total cash equivalents $ 20,000 $ 20,000 $ — $ — December 31, 2017: Cash equivalents: Money market funds $ 27,000 $ 27,000 $ — $ — Total cash equivalents $ 27,000 $ 27,000 $ — $ —
Schedule of Fair Value of Liabilities Measured on Recurring Basis Using Unobservable Inputs	. The following table sets forth the changes in the estimated fair value of the Company’s liabilities measured on a recurring basis using significant unobservable inputs (Level 3): Six Months Ended June 30, ( in thousands 2018 2017 Fair value measurement at beginning of period $ 67,941 $ 67,501 Contingent consideration liability recorded upon acquisition 6,663 533 Change in fair value measurement 794 (657 ) Changes resulting from foreign currency fluctuations 25 44 Contingent consideration paid or settled (9,000 ) (30,000 ) Fair value measurement at end of period $ 66,423 $ 37,421

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and intangible assets	Goodwill and intangible assets consisted of the following: Weighted- Average Amortization ( in thousands, except years Period Gross Accumulated Intangible June 30, 2018: (in years) Amount Amortization Assets, net Intangible assets subject to amortization: Developed technology 8 $ 271,748 $ (115,442 ) $ 156,306 Manufacturing know-how and trade secrets 13 30,831 (16,728 ) 14,103 Trade name and trademarks 9 25,500 (12,218 ) 13,282 Customer relationships 9 143,847 (51,220 ) 92,627 Total intangible assets subject to amortization 9 $ 471,926 $ (195,608 ) $ 276,318 Intangible assets not subject to amortization: Goodwill $ 560,751 Total goodwill and intangible assets, net $ 837,069 Weighted- Average Amortization Period Gross Accumulated Intangible December 31, 2017: (in years) Amount Amortization Assets, net Intangible assets subject to amortization: Developed technology 8 $ 271,748 $ (98,693 ) $ 173,055 Manufacturing know-how and trade secrets 13 30,653 (15,542 ) 15,111 Trade name and trademarks 9 25,200 (10,559 ) 14,641 Customer relationships 9 122,249 (44,282 ) 77,967 Total intangible assets subject to amortization 9 $ 449,850 $ (169,076 ) $ 280,774 Intangible assets not subject to amortization: Goodwill $ 536,926 Total goodwill and intangible assets, net $ 817,700
Schedule of changes in the carrying value of goodwill	The following table summarizes the changes in the carrying value of the Company’s goodwill: ( in thousands December 31, 2017 Gross goodwill $ 545,226 Accumulated impairment loss (8,300 ) 536,926 Changes to gross goodwill Increases recorded in business combinations 26,303 Changes in purchase price allocation (1,075 ) Changes resulting from foreign currency fluctuations (1,403 ) 23,825 June 30, 2018 Gross goodwill 569,051 Accumulated impairment loss (8,300 ) $ 560,751
Future amortization expense related to intangible assets	Total future amortization expense related to intangible assets subject to amortization at June 30, 2018 is set forth in the table below: ( in thousands Remaining 2018 $ 26,406 2019 51,638 2020 51,016 2021 48,956 2022 41,545 Thereafter through 2031 56,757 Total future amortization expense $ 276,318

Business Combinations (Tables)

Business Combinations (Tables)	6 Months Ended
	Jun. 30, 2018
Business Combination Description [Abstract]
Reconciliation of equity attributable to the non-controlling interests	The following is a reconciliation of equity (net assets) attributable to the non-controlling interest: Six Months Ended June 30, ( in thousands 2018 2017 Non-controlling interest at beginning of period $ 3,845 $ 5,588 Acquired non-controlling interest reclassified to additional paid-in capital (3,845 ) — Less: Net loss attributable to the non-controlling interest — (875 ) Non-controlling interest at end of period $ — $ 4,713
Summary of assets and liabilities included in the accompanying consolidated balance sheet	Total assets and liabilities of Progentix as a VIE included in the accompanying Consolidated Balance Sheets are as follows: ( in thousands June 30, 2018 December 31, 2017 Total current assets $ — $ 670 Identifiable intangible assets, net — 8,752 Goodwill — 12,654 Accounts payable and accrued expenses — 562 Deferred tax liabilities, net — 331 Non-controlling interest — 3,845

Indebtedness (Tables)

Indebtedness (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Carrying Value of Senior Convertible Notes	The carrying values of the Company’s Senior Convertible Notes due 2021 are as follows: ( in thousands June 30, 2018 December 31, 2017 2.25% Senior Convertible Notes due 2021: Principal amount 650,000 650,000 Unamortized debt discount (48,587 ) (56,839 ) Unamortized debt issuance costs (8,832 ) (10,241 ) Total Senior Convertible Notes $ 592,581 $ 582,920

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Compensation Costs Included in Statement of Income for all Stock-based Compensation Arrangements	The compensation cost that has been included in the Consolidated Statements of Operations for all stock-based compensation arrangements was as follows: Three Months Ended June 30, Six Months Ended June 30, ( in thousands 2018 2017 2018 2017 Sales, marketing and administrative expense $ 5,929 $ 7,891 $ 9,444 $ 14,686 Research and development expense 838 428 1,338 567 Cost of revenue 93 75 212 158 Stock-based compensation expense before taxes 6,860 8,394 10,994 15,411 Related income tax benefits (1,715 ) (3,190 ) (2,749 ) (5,856 ) Stock-based compensation expense, net of taxes $ 5,145 $ 5,204 $ 8,245 $ 9,555
Weighted Average Assumptions Used to Estimate Fair Value of Stock Purchase Rights under ESPP	The weighted average assumptions used to estimate the fair value of stock purchase rights under the employee stock purchase plan (“ESPP”) are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 ESPP Volatility 30 % 21 % 34 % 23 % Expected term (years) 0.5 0.5 0.5 0.5 Risk free interest rate 1.8 % 0.8 % 1.4 % 0.6 % Expected dividend yield — % — % — % — %

Business Segment, Product and G

Business Segment, Product and Geographic Information (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Schedule of Revenue by Product Lines	Revenue by product line was as follows: Three Months Ended June 30, Six Months Ended June 30, ( in thousands 2018 2017 2018 2017 Spinal hardware $ 202,060 $ 184,725 $ 387,961 $ 359,812 Surgical support 79,504 74,674 154,125 148,600 Total revenue $ 281,564 $ 259,399 $ 542,086 $ 508,412
Schedule of Revenue and Net Property and Equipment by Geographical Area	Revenue and property and equipment, net, by geographic area were as follows: Revenue Property and Equipment, Net Three Months Ended June 30, Six Months Ended June 30, June 30, December 31, ( in thousands 2018 2017 2018 2017 2018 2017 United States $ 226,949 $ 215,972 $ 440,252 $ 429,329 $ 195,980 $ 179,891 International (excludes Puerto Rico) 54,615 43,427 101,834 79,083 35,753 35,435 Total $ 281,564 $ 259,399 $ 542,086 $ 508,412 $ 231,733 $ 215,326

Description of Business and B29

Description of Business and Basis of Presentation (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Schedule Of Description Of Business And Basis Of Presentation [Line Items]
Cumulative effect of change on retained earnings	$ (10,839)		$ (10,839)		$ 4,762
Inventory, finished goods	244,400		244,400		232,400
Inventory, work in progress	10,200		10,200		9,800
Inventory, raw materials	5,200		5,200		5,000
Translation Adjustment Functional to Reporting Currency, Net of Tax	8,900		8,900		6,900
Product shipment costs	6,400	$ 5,700	12,300	$ 11,600
Business transition costs	3,998	1,369	6,251	1,424
2017 and 2016 Acquisitions [Member]
Schedule Of Description Of Business And Basis Of Presentation [Line Items]
Business transition costs	$ 600	$ 700	$ 800	$ (700)
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Schedule Of Description Of Business And Basis Of Presentation [Line Items]
Cumulative effect of change on retained earnings					$ 300

Description of Business and B30

Description of Business and Basis of Presentation - Summary of Condensed Presentation Impact of Adoption of ASC 606 Adoption on the Company's Previously Reported Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowances on accounts receivable	$ (16,782)	$ (13,026)
Inventory, net	259,819	247,138
Total current assets	571,579	560,063
Other assets	24,607	39,117
Total assets	1,672,337	1,640,140
Accounts payable and accrued liabilities	89,534	75,767
Accrued payroll and related expenses	51,128	55,618
Total current liabilities	204,001	161,395
Deferred and income tax liabilities, non-current	9,525	18,870
Other long-term liabilities	85,067	77,539
Total NuVasive, Inc. stockholders’ equity	781,163	795,571
Non-controlling interest		3,845
Total equity	781,163	799,416
Total liabilities and equity	$ 1,672,337	1,640,140
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accounts receivable, gross		213,246
Allowances on accounts receivable		(13,026)
Inventory, net		247,138
Other current assets		112,705
Total current assets		560,063
Other assets		1,080,077
Total assets		1,640,140
Accounts payable and accrued liabilities		75,767
Accrued payroll and related expenses		55,618
Other current liabilities		30,010
Total current liabilities		161,395
Deferred and income tax liabilities, non-current		18,870
Other long-term liabilities		660,459
Total NuVasive, Inc. stockholders’ equity		795,571
Non-controlling interest		3,845
Total equity		799,416
Total liabilities and equity		1,640,140
Accounting Standards Update 2014-09 [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accounts receivable, gross		212,709
Allowances on accounts receivable		(13,669)
Inventory, net		247,245
Other current assets		112,705
Total current assets		558,990
Other assets		1,080,077
Total assets		1,639,067
Accounts payable and accrued liabilities		75,076
Accrued payroll and related expenses		55,582
Other current liabilities		30,010
Total current liabilities		160,668
Deferred and income tax liabilities, non-current		18,786
Other long-term liabilities		660,459
Total NuVasive, Inc. stockholders’ equity		795,309
Non-controlling interest		3,845
Total equity		799,154
Total liabilities and equity		1,639,067
Accounting Standards Update 2014-09 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accounts receivable, gross		537
Allowances on accounts receivable		643
Inventory, net		(107)
Total current assets		1,073
Total assets		1,073
Accounts payable and accrued liabilities		691
Accrued payroll and related expenses		36
Total current liabilities		727
Deferred and income tax liabilities, non-current		84
Total NuVasive, Inc. stockholders’ equity		262
Total equity		262
Total liabilities and equity		$ 1,073

Description of Business and B31

Description of Business and Basis of Presentation - Summary of Condensed Presentation Impact of Adoption of ASC 606 on the Company's Previously Reported Unaudited Consolidated Statement of Operations and Comprehensive Income (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue
Product revenue	$ 252,687	$ 237,824	$ 486,202	$ 462,779
Service revenue	28,877	21,575	55,884	45,633
Total revenue	281,564	259,399	542,086	508,412
Cost of revenue (excluding below amortization of intangible assets)
Cost of products sold	58,202	50,535	113,393	96,436
Cost of services	18,854	15,651	37,477	31,193
Total cost of revenue	77,056	66,186	150,870	127,629
Gross profit	204,508	193,213	391,216	380,783
Operating expenses:
Sales, marketing and administrative	145,658	138,967	292,424	279,335
Total operating expenses	175,945	164,257	380,875	329,155
Total interest and other expense, net	(12,219)	(10,445)	(31,255)	(19,849)
Income tax (expense) benefit	(4,813)	(6,776)	5,313	(8,061)
Consolidated net income (loss)	11,531	11,735	(15,601)	23,718
Add back net loss attributable to non-controlling interest		(432)		(875)
Net income (loss) attributable to NuVasive, Inc.	$ 11,531	$ 12,167	$ (15,601)	$ 24,593
Net income per share attributable to NuVasive, Inc.:
Basic	$ 0.22	$ 0.24	$ (0.30)	$ 0.48
Diluted	$ 0.22	$ 0.21	$ (0.30)	$ 0.42
Comprehensive income attributable to NuVasive, Inc.	$ 7,009	$ 12,810	$ (17,544)	$ 27,093
Accounting Standards Update 2014-09 [Member]
Revenue
Product revenue		237,824	462,779
Service revenue		21,575	45,633
Total revenue		259,399	508,412
Cost of revenue (excluding below amortization of intangible assets)
Cost of products sold		50,535	96,436
Cost of services		15,651	31,193
Total cost of revenue		66,186	127,629
Gross profit		193,213	380,783
Operating expenses:
Sales, marketing and administrative		138,967	279,335
Other operating expenses		25,290	49,820
Total operating expenses		164,257	329,155
Total interest and other expense, net		(10,445)	(19,849)
Income tax (expense) benefit		(6,776)	(8,061)
Consolidated net income (loss)		11,735	23,718
Add back net loss attributable to non-controlling interest		(432)	(875)
Net income (loss) attributable to NuVasive, Inc.		$ 12,167	$ 24,593
Net income per share attributable to NuVasive, Inc.:
Basic		$ 0.24	$ 0.48
Diluted		$ 0.21	$ 0.42
Comprehensive income attributable to NuVasive, Inc.		$ 12,810	$ 27,093
Accounting Standards Update 2014-09 [Member] | Scenario, Previously Reported [Member]
Revenue
Product revenue		238,998	464,804
Service revenue		21,575	45,633
Total revenue		260,573	510,437
Cost of revenue (excluding below amortization of intangible assets)
Cost of products sold		50,770	96,841
Cost of services		15,651	31,193
Total cost of revenue		66,421	128,034
Gross profit		194,152	382,403
Operating expenses:
Sales, marketing and administrative		139,109	279,611
Other operating expenses		25,290	49,820
Total operating expenses		164,399	329,431
Total interest and other expense, net		(10,445)	(19,849)
Income tax (expense) benefit		(7,079)	(8,569)
Consolidated net income (loss)		12,229	24,554
Add back net loss attributable to non-controlling interest		(432)	(875)
Net income (loss) attributable to NuVasive, Inc.		$ 12,661	$ 25,429
Net income per share attributable to NuVasive, Inc.:
Basic		$ 0.25	$ 0.50
Diluted		$ 0.22	$ 0.44
Comprehensive income attributable to NuVasive, Inc.		$ 13,304	$ 27,929
Accounting Standards Update 2014-09 [Member] | Restatement Adjustment [Member]
Revenue
Product revenue		(1,174)	(2,025)
Total revenue		(1,174)	(2,025)
Cost of revenue (excluding below amortization of intangible assets)
Cost of products sold		(235)	(405)
Total cost of revenue		(235)	(405)
Gross profit		(939)	(1,620)
Operating expenses:
Sales, marketing and administrative		(142)	(276)
Total operating expenses		(142)	(276)
Income tax (expense) benefit		303	508
Consolidated net income (loss)		(494)	(836)
Net income (loss) attributable to NuVasive, Inc.		$ (494)	$ (836)
Net income per share attributable to NuVasive, Inc.:
Basic		$ (0.01)	$ (0.02)
Diluted		$ (0.01)	$ (0.01)
Comprehensive income attributable to NuVasive, Inc.		$ (494)	$ (836)

Description of Business and B32

Description of Business and Basis of Presentation - Summary of Condensed Presentation Impact of Adoption of ASC 606 Adoption on the Company's Previously Reported Unaudited Consolidated Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Consolidated net (loss) income	$ 11,531	$ 11,735	$ (15,601)	$ 23,718
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Reserves on current assets			9,444	64
Deferred income tax benefit			(6,593)	(3,077)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable			852	(15,823)
Inventory			(19,615)	(29,417)
Prepaid expenses and other current assets			(2,141)	(2,543)
Accounts payable and accrued liabilities			9,031	4,868
Litigation liability			2,150
Accrued payroll and related expenses			(6,358)	(2,059)
Income taxes			(53)	10,172
Net cash provided by operating activities			77,218	67,064
Net cash used in investing activities			(113,151)	(84,802)
Net cash used in financing activities			31,044	(6,480)
Effect of exchange rate changes on cash			(837)	1,449
Decrease in cash, cash equivalents, restricted cash and investments			(5,726)	$ (22,769)
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Consolidated net (loss) income		11,735	23,718
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Reserves on current assets			64
Deferred income tax benefit			(3,077)
Other adjustments to reconcile net income			92,361
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable			(15,823)
Inventory			(29,417)
Prepaid expenses and other current assets			(2,543)
Accounts payable and accrued liabilities			4,868
Litigation liability			(11,200)
Accrued payroll and related expenses			(2,059)
Income taxes			10,172
Net cash provided by operating activities			67,064
Net cash used in investing activities			(84,802)
Net cash used in financing activities			(6,480)
Effect of exchange rate changes on cash			1,449
Decrease in cash, cash equivalents, restricted cash and investments			(22,769)
Accounting Standards Update 2014-09 [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Consolidated net (loss) income		12,229	24,554
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Reserves on current assets			(95)
Deferred income tax benefit			(2,570)
Other adjustments to reconcile net income			92,361
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable			(17,586)
Inventory			(29,012)
Prepaid expenses and other current assets			(2,543)
Accounts payable and accrued liabilities			4,987
Litigation liability			(11,200)
Accrued payroll and related expenses			(2,004)
Income taxes			10,172
Net cash provided by operating activities			67,064
Net cash used in investing activities			(84,802)
Net cash used in financing activities			(6,480)
Effect of exchange rate changes on cash			1,449
Decrease in cash, cash equivalents, restricted cash and investments			(22,769)
Accounting Standards Update 2014-09 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Consolidated net (loss) income		$ (494)	(836)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Reserves on current assets			159
Deferred income tax benefit			(507)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable			1,763
Inventory			(405)
Accounts payable and accrued liabilities			(119)
Accrued payroll and related expenses			$ (55)

Net Income (Loss) Per Share - C

Net Income (Loss) Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net income (loss) attributable to NuVasive, Inc.	$ 11,531	$ 12,167	$ (15,601)	$ 24,593
Denominator for basic and diluted net income (loss) per share:
Weighted average common shares outstanding for basic	51,356	51,082	51,292	50,825
Dilutive potential common stock outstanding:
Warrants		2,929		2,987
Senior Convertible Notes		2,825		2,681
Weighted average common shares outstanding for diluted	51,956	58,330	51,292	58,059
Basic net income (loss) per share attributable to NuVasive, Inc.	$ 0.22	$ 0.24	$ (0.30)	$ 0.48
Diluted net income (loss) per share attributable to NuVasive, Inc.	$ 0.22	$ 0.21	$ (0.30)	$ 0.42
Stock Options and Employee Stock Purchase Plan [Member]
Dilutive potential common stock outstanding:
Stock options and employee stock purchase plan	30	138		180
Restricted Stock Units [Member]
Dilutive potential common stock outstanding:
Stock options and employee stock purchase plan	570	1,356		1,386

Net Income (Loss) Per Share - A

Net Income (Loss) Per Share - Anti-dilutive Common Stock Equivalents Not Included in Calculation of Net Income (Loss) Per Diluted Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	21,891	10,906	23,011	10,936
Stock Options, Employee Stock Purchase Plan, and Restricted Stock Units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	161	41	1,281	71
Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	10,865	10,865	10,865	10,865
Senior Convertible Notes [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	10,865		10,865

Financial Instruments and Fai35

Financial Instruments and Fair Value Measurements (Details Textual)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)investment	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)investment	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)investment
Business Acquisition [Line Items]
Net currency exchange gains (losses) from derivatives instruments	$ (2,200,000)	$ (500,000)	$ (2,500,000)	$ (300,000)
Unrealized loss position investment | investment	0		0		0
Impairment charges recorded for earnings			$ 0		$ 0
Contingent consideration liability	$ 12,214,000		12,214,000		18,952,000
Impairment charge on strategic investment			9,004,000
Contingent Consideration Liabilities [Member]
Business Acquisition [Line Items]
Contingent consideration liability	66,400,000		66,400,000		67,900,000
Quoted Price in Active Market (Level 1) [Member] | Senior Convertible Notes due 2021 [Member]
Business Acquisition [Line Items]
Debt instrument, fair value disclosure	710,900,000		710,900,000		779,500,000
Foreign Exchange Forward [Member]
Business Acquisition [Line Items]
Notional principal amount	15,900,000		15,900,000		14,300,000
Foreign Exchange Forward [Member] | Other Current Assets or Other Current Liabilities [Member]
Business Acquisition [Line Items]
Fair value of derivative instrument asset (liability)	(100,000)		(100,000)		$ (100,000)
Foreign Exchange Forward [Member] | Other (Expense) Income [Member]
Business Acquisition [Line Items]
Net gains (losses) recognized on derivative instruments	$ 700,000	$ (900,000)	$ 300,000	$ (1,300,000)

Financial Instruments and Fai36

Financial Instruments and Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value Measurements on Recurring Basis [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities	$ 20,000	$ 27,000
Money Market Funds [Member]
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities	20,000	27,000
Quoted Price in Active Market (Level 1) [Member]
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities	20,000	27,000
Quoted Price in Active Market (Level 1) [Member] | Money Market Funds [Member]
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities	$ 20,000	$ 27,000

Financial Instruments and Fai37

Financial Instruments and Fair Value Measurements - Schedule of Fair Value of Liabilities Measured on Recurring Basis Using Unobservable Inputs (Details) - Contingent Consideration Liabilities [Member] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value measurement at beginning of period	$ 67,941	$ 67,501
Contingent consideration liability recorded upon acquisition	6,663	533
Change in fair value measurement	794	(657)
Changes resulting from foreign currency fluctuations	25	44
Contingent consideration paid or settled	(9,000)	(30,000)
Fair value measurement at end of period	$ 66,423	$ 37,421

Goodwill and Intangible Asset38

Goodwill and Intangible Assets - Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Intangible assets subject to amortization:
Weighted Average Amortization Period	9 years	9 years
Gross Amount	$ 471,926	$ 449,850
Accumulated Amortization	(195,608)	(169,076)
Intangible Assets, net	276,318	280,774
Intangible assets not subject to amortization:
Goodwill	560,751	536,926
Total goodwill and intangible assets, net	$ 837,069	$ 817,700
Developed Technology [Member]
Intangible assets subject to amortization:
Weighted Average Amortization Period	8 years	8 years
Gross Amount	$ 271,748	$ 271,748
Accumulated Amortization	(115,442)	(98,693)
Intangible Assets, net	$ 156,306	$ 173,055
Manufacturing know-how and trade secrets [Member]
Intangible assets subject to amortization:
Weighted Average Amortization Period	13 years	13 years
Gross Amount	$ 30,831	$ 30,653
Accumulated Amortization	(16,728)	(15,542)
Intangible Assets, net	$ 14,103	$ 15,111
Trade name and trademarks [Member]
Intangible assets subject to amortization:
Weighted Average Amortization Period	9 years	9 years
Gross Amount	$ 25,500	$ 25,200
Accumulated Amortization	(12,218)	(10,559)
Intangible Assets, net	$ 13,282	$ 14,641
Customer relationships [Member]
Intangible assets subject to amortization:
Weighted Average Amortization Period	9 years	9 years
Gross Amount	$ 143,847	$ 122,249
Accumulated Amortization	(51,220)	(44,282)
Intangible Assets, net	$ 92,627	$ 77,967

Goodwill and Intangible Asset39

Goodwill and Intangible Assets - Schedule of Changes in the Carrying Value of Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Gross goodwill	$ 569,051	$ 545,226
Accumulated impairment loss	(8,300)	(8,300)
Goodwill	560,751	$ 536,926
Changes to gross goodwill
Increases recorded in business combinations	26,303
Changes in purchase price allocation	(1,075)
Changes resulting from foreign currency fluctuations	(1,403)
Goodwill period increase (decrease)	$ 23,825

Goodwill and Intangible Asset40

Goodwill and Intangible Assets (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense related to intangible assets	$ 13.5	$ 12.2	$ 26.9	$ 25.2

Goodwill and Intangible Asset41

Goodwill and Intangible Assets - Future Amortization Expense Related to Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Future amortization expense related to intangible assets
Remaining 2,018	$ 26,406
2,019	51,638
2,020	51,016
2,021	48,956
2,022	41,545
Thereafter through 2031	56,757
Intangible Assets, net	$ 276,318	$ 280,774

Business Combinations (Details

Business Combinations (Details Textual) - Progentix Orthobiology [Member] - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2009	Jan. 31, 2018
Business Acquisition [Line Items]
Percentage of ownership Interests acquired			60.00%
Advanced loan accordance to loan agreement	$ 5,300,000
Accrued interest rate of loan	6.00%
Ownership percentage	100.00%
Preferred Stock Purchase Agreement [Member]
Business Acquisition [Line Items]
Percentage of ownership Interests acquired		40.00%
Cash payment on purchase of outstanding shares		$ 10,000,000

Reconciliation of Equity Attrib

Reconciliation of Equity Attributable to the Non-controlling Interests (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reconciliation of equity attributable to the non-controlling interests
Non-controlling interest at beginning of period		$ 3,845
Less: Net loss attributable to the non-controlling interest	$ (432)		$ (875)
Variable Interest Entity [Member]
Reconciliation of equity attributable to the non-controlling interests
Non-controlling interest at beginning of period		3,845	5,588
Acquired non-controlling interest reclassified to additional paid-in capital		$ (3,845)
Less: Net loss attributable to the non-controlling interest			(875)
Non-controlling interest at end of period	$ 4,713		$ 4,713

Business Combinations Total ass

Business Combinations Total assets and liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Total current assets	$ 571,579	$ 560,063
Goodwill	$ 560,751	536,926
Non-controlling interest		3,845
Variable Interest Entity [Member]
Business Acquisition [Line Items]
Non-controlling interest		3,845	$ 4,713	$ 5,588
Variable Interest Entity [Member] | Progentix Orthobiology [Member]
Business Acquisition [Line Items]
Total current assets		670
Identifiable intangible assets, net		8,752
Goodwill		12,654
Accounts payable and accrued expenses		562
Deferred tax liabilities, net		331
Non-controlling interest		$ 3,845

Carrying Value of Senior Conver

Carrying Value of Senior Convertible Notes Due 2021 (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017	Mar. 31, 2016
Debt Instrument [Line Items]
Total Senior Convertible Notes	$ 592,581,000	$ 582,920,000
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member]
Debt Instrument [Line Items]
Principal amount	650,000,000	650,000,000	$ 650,000,000
Unamortized debt discount	(48,587,000)	(56,839,000)
Unamortized debt issuance costs	$ (8,832,000)	$ (10,241,000)

Carrying Value of Senior Conv46

Carrying Value of Senior Convertible Notes Due 2021 (Parenthetical) (Details)	Jun. 30, 2018	Dec. 31, 2017	Mar. 31, 2016
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes	2.25%	2.25%	2.25%

Indebtedness (Details Textual)

Indebtedness (Details Textual)	1 Months Ended			3 Months Ended		6 Months Ended		9 Months Ended	12 Months Ended
	Apr. 30, 2017USD ($)	Mar. 31, 2016USD ($)$ / shares	Jun. 30, 2011USD ($)$ / shares	Jun. 30, 2018USD ($)$ / sharesshares	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)d$ / sharesshares	Jun. 30, 2017USD ($)	Sep. 30, 2017USD ($)shares	Dec. 31, 2016USD ($)	Dec. 31, 2011$ / sharesshares	Dec. 31, 2017USD ($)
Revolving Senior Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes				4.05%		4.05%
Credit facility, maximum borrowing capacity	$ 500,000,000
Credit facility, expiration date						2022-04
Loan outstanding				$ 37,000,000		$ 37,000,000
Revolving Senior Credit Facility [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Credit facility bear interest rate	1.00%					1.75%
Revolving Senior Credit Facility [Member] | Federal Funds Effective Rate [Member]
Debt Instrument [Line Items]
Credit facility bear interest rate	0.50%
Multicurrency Borrowings [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 100,000,000
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	50,000,000
Swing Line Loans [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 5,000,000
2021 Warrants [Member]
Debt Instrument [Line Items]
Cash proceeds from the sale of warrants		$ 44,900,000
Warrant strike price | $ / shares		$ 80
Warrants Two Thousand Seventeen
Debt Instrument [Line Items]
Class of warrant or rights expiry month and year						2017-09
Warrant strike price | $ / shares				$ 988.51		$ 988.51
Warrants Two Thousand Seventeen | Series A Convertible Participating Preferred Stock [Member]
Debt Instrument [Line Items]
Number of common stock shares preferred stock convertible into | shares				20		20
2021 Hedge [Member]
Debt Instrument [Line Items]
Number of common stock to be purchased | shares						10,865,270
Stock price | $ / shares		$ 59.82
Derivative, maturity date		Mar. 15, 2021
2017 Hedge [Member]
Debt Instrument [Line Items]
Number of common stock to be purchased | shares										9,553,096
Stock price | $ / shares										$ 42.13
Minimum [Member] | Revolving Senior Credit Facility [Member]
Debt Instrument [Line Items]
Unused line fee	0.20%
Minimum [Member] | Revolving Senior Credit Facility [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Credit facility bear interest rate	0.00%
Minimum [Member] | Revolving Senior Credit Facility [Member] | Eurocurrency [Member]
Debt Instrument [Line Items]
Credit facility bear interest rate	1.00%
Minimum [Member] | 2021 Warrants [Member]
Debt Instrument [Line Items]
Class of warrant or rights expiry month and year								2021-06
Maximum [Member] | Revolving Senior Credit Facility [Member]
Debt Instrument [Line Items]
Unused line fee	0.35%
Maximum [Member] | Revolving Senior Credit Facility [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Credit facility bear interest rate	1.00%
Maximum [Member] | Revolving Senior Credit Facility [Member] | Eurocurrency [Member]
Debt Instrument [Line Items]
Credit facility bear interest rate	2.00%
Maximum [Member] | 2021 Warrants [Member]
Debt Instrument [Line Items]
Class of warrant or rights expiry month and year								2021-12
Maximum [Member] | Warrants Two Thousand Seventeen
Debt Instrument [Line Items]
Class of warrant or rights expiry month and year						2018-01
Maximum [Member] | Warrants Two Thousand Seventeen | Series A Convertible Participating Preferred Stock [Member]
Debt Instrument [Line Items]
Number of preferred or common stock into which the warrants is converted | shares				477,654		477,654
Additional Paid-in Capital [Member] | 2021 Hedge [Member]
Debt Instrument [Line Items]
Cost of hedge transaction									$ 111,200,000
Common Shares [Member] | Maximum [Member] | 2021 Warrants [Member]
Debt Instrument [Line Items]
Number of preferred or common stock into which the warrants is converted | shares								10,865,270
Common Shares [Member] | Maximum [Member] | Warrants Two Thousand Seventeen
Debt Instrument [Line Items]
Number of preferred or common stock into which the warrants is converted | shares				9,553,080		9,553,080
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member]
Debt Instrument [Line Items]
Principal amount		$ 650,000,000		$ 650,000,000		$ 650,000,000					$ 650,000,000
Proceeds from issuance of convertible debt, net of issuance costs		$ 634,100,000
Interest rate on convertible notes		2.25%		2.25%		2.25%					2.25%
Debt instrument, maturity date		Mar. 15, 2021
Initial conversion rate adjustment, shares		16.7158
Principal amount of debt considered for conversion rate		$ 1,000
Initial conversion price of convertible notes | $ / shares		$ 59.82
Contractual coupon interest expense				$ 3,700,000	$ 3,700,000	$ 7,300,000	$ 7,300,000
Amortization of debt discount (premium)				4,200,000	3,900,000	8,300,000	7,800,000
Amortization of debt issuance costs				$ 700,000	700,000	$ 1,400,000	1,300,000
Effective interest rate				5.80%		5.80%
Debt redemption price percentage						100.00%
Principal payments due								$ 0
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member] | Scenario Two [Member]
Debt Instrument [Line Items]
Consecutive trading days considered for debt conversion | d						5
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percentage of conversion price						130.00%
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member] | Minimum [Member] | Scenario One [Member]
Debt Instrument [Line Items]
Consecutive trading days considered for debt conversion | d						20
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage of conversion price						98.00%
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member] | Maximum [Member] | Scenario One [Member]
Debt Instrument [Line Items]
Consecutive trading days considered for debt conversion | d						30
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member] | Additional Paid-in Capital [Member]
Debt Instrument [Line Items]
Amount reclassified to stockholders' equity									84,800,000
2.75% Senior Convertible Notes [Member] | Convertible Notes due 2017 [Member]
Debt Instrument [Line Items]
Principal amount			$ 402,500,000
Interest rate on convertible notes			2.75%
Debt instrument, maturity date			Jul. 1, 2017
Initial conversion rate adjustment, shares			23.7344
Principal amount of debt considered for conversion rate			$ 1,000
Initial conversion price of convertible notes | $ / shares			$ 42.13
Contractual coupon interest expense					400,000		900,000
Amortization of debt discount (premium)					700,000		1,400,000
Amortization of debt issuance costs					$ 100,000		$ 200,000
Effective interest rate				8.00%		8.00%
2.75% Senior Convertible Notes [Member] | Convertible Notes due 2017 [Member] | Other Expense [Member]
Debt Instrument [Line Items]
Cumulative loss on repurchase of senior convertible notes									$ 19,100,000

Stock-Based Compensation - Comp

Stock-Based Compensation - Compensation Costs Included in Statement of Income for all Stock-based Compensation Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 6,860	$ 8,394	$ 10,994	$ 15,411
Related income tax benefits	(1,715)	(3,190)	(2,749)	(5,856)
Stock-based compensation expense, net of taxes	5,145	5,204	8,245	9,555
Sales, Marketing and Administrative Expense [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	5,929	7,891	9,444	14,686
Research and Development Expense [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	838	428	1,338	567
Cost of Revenue [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense before taxes	$ 93	$ 75	$ 212	$ 158

Stock-Based Compensation (Detai

Stock-Based Compensation (Details Textual) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted		0
Number of common stock issued to exercise stock options	43,000	103,000	232,000
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum percentage of annual compensation	15.00%	15.00%
Maximum amount withheld to purchase shares of the company		$ 21,250
Percentage of issuance price of stock under the stock issuance program		85.00%
ESPP offering period		6 months
Performance Based Restricted Stock Units (PRSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unamortized cost related to share-based compensation	$ 53,900,000	$ 53,900,000
Weighted average contractual term		2 years 3 months 18 days
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unamortized cost related to share-based compensation	$ 53,900,000	$ 53,900,000
Weighted average contractual term		2 years 3 months 18 days
Number of shares of common stock issued upon vesting of RSUs	38,000	150,000	359,000

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Assumptions Used to Estimate Fair Value of Stock Purchase Rights under ESPP (Details) - ESPP [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted average assumptions used to estimate fair value of stock options granted and stock purchase rights under ESPP
Volatility	30.00%	21.00%	34.00%	23.00%
Expected term (years)	6 months	6 months	6 months	6 months
Risk free interest rate	1.80%	0.80%	1.40%	0.60%

Income Taxes (Details Textual)

Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent		25.00%
Tax cuts and jobs act 2017, executive compensation related deferred taxes and federal tax revaluation impact write-down		$ 0.3
Tax cuts and jobs act 2017, increase in effective income tax rate due to deferred tax and federal tax revaluation impact write-down	1.70%		0.50%
Deferred tax assets, in process research and development		0.9
Remaining unrecognized tax benefits		$ 6.5

Business Segment, Product and52

Business Segment, Product and Geographic Information (Details Textual)	6 Months Ended
	Jun. 30, 2018segment
Segment Reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1

Business Segment, Product and53

Business Segment, Product and Geographic Information - Schedule of Revenue by Product Lines (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Entity Wide Information Revenue From External Customer [Line Items]
Total Revenue	$ 281,564	$ 259,399	$ 542,086	$ 508,412
Spinal Hardware [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Total Revenue	202,060	184,725	387,961	359,812
Surgical Support [Member]
Entity Wide Information Revenue From External Customer [Line Items]
Total Revenue	$ 79,504	$ 74,674	$ 154,125	$ 148,600

Business Segment, Product and54

Business Segment, Product and Geographic Information - Schedule of Revenue and Net Property and Equipment by Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Revenues and Net Property and Equipment by Geographical Areas [Line Items]
Revenue	$ 281,564	$ 259,399	$ 542,086	$ 508,412
Property and Equipment, Net	231,733		231,733		$ 215,326
United States
Revenues and Net Property and Equipment by Geographical Areas [Line Items]
Revenue	226,949	215,972	440,252	429,329
Property and Equipment, Net	195,980		195,980		179,891
International [Member]
Revenues and Net Property and Equipment by Geographical Areas [Line Items]
Revenue	54,615	$ 43,427	101,834	$ 79,083
Property and Equipment, Net	$ 35,753		$ 35,753		$ 35,435

Commitments (Details Textual)

Commitments (Details Textual) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Licensing and Purchasing Agreements [Member]
Commitments And Contingencies Disclosure [Line Items]
Obligation under consultancy arrangements	$ 47.2
Revenue-based milestone period	achieved prior to 2027
Executive Severance Plans [Member]
Commitments And Contingencies Disclosure [Line Items]
Other commitments, future minimum payments, remainder of fiscal year	$ 23.3

Contingencies (Details)

Contingencies (Details) - USD ($)	Feb. 13, 2018	Jul. 05, 2016	Mar. 18, 2016	Feb. 19, 2016	May 31, 2018	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Mar. 31, 2018
Loss Contingencies [Line Items]
Litigation accrual adjustment						$ 1,195,000	$ (27,800,000)
Litigation accrual						10,300,000	10,300,000	$ 8,150,000
Madsen Medical, Inc. Litigation [Member]
Loss Contingencies [Line Items]
Settlement agreement, consideration					$ 27,800,000	27,800,000
Litigation accrual adjustment						1,200,000
Litigation accrual					$ 27,800,000	29,000,000	$ 29,000,000		$ 29,000,000
Jury award			$ 27,800,000
Loss contingency, settlement agreement, court							On March 18, 2016, the trial court entered judgment in favor of MMI in the amount of $27.8 million, which amount excluded the $14.0 million disgorgement awarded by the jury.
Madsen Medical, Inc. Litigation [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss								0	0
Madsen Medical, Inc. Litigation [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss									$ 29,000,000
Madsen Medical, Inc. Litigation [Member] | Loss Profits for Tortious Interference [Member]
Loss Contingencies [Line Items]
Jury award				$ 7,500,000
Madsen Medical, Inc. Litigation [Member] | Unjust Enrichment [Member]
Loss Contingencies [Line Items]
Jury award				14,000,000
Madsen Medical, Inc. Litigation [Member] | Punitive Damages [Member]
Loss Contingencies [Line Items]
Jury award				20,000,000
Madsen Medical, Inc. Litigation [Member] | Damages for Breach of Contract [Member]
Loss Contingencies [Line Items]
Jury award				$ 300,000
Madsen Medical, Inc. Litigation [Member] | Attorney Fees And Costs [Member]
Loss Contingencies [Line Items]
Jury award		$ 1,100,000
Securities Litigation [Member]
Loss Contingencies [Line Items]
Settlement agreement, consideration	$ 7,900,000
Litigation accrual						$ 7,900,000	$ 7,900,000	7,900,000
Expected insurance proceeds							$ 7,900,000	$ 7,900,000