Description of Business and Basis of Presentation	3 Months Ended
Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	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 is focused on developing minimally-disruptive surgical products and procedurally-integrated solutions for the spine. NuVasive's principal product offering includes a minimally-disruptive surgical platform called "Maximum Access Surgery", or "MAS^®", as well as an offering of biologics, cervical and motion preservation products. 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 reproducible outcomes for the surgeon. The platform includes a proprietary software-driven nerve detection and avoidance systems, NVM5 and NVJJB, and Intra-Operative Monitoring ("IOM") support; MaXcess^®, an integrated split-blade retractor system; and a wide variety of specialized implants. The individual components of NuVasive's MAS platform, and many of the Company's products, can also be used in open or traditional spine surgery. The Company continues to focus significant 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 primary business model is to loan its MAS systems to surgeons and hospitals who purchase implants, biologics and disposables for use in individual procedures. In addition, for larger customers, the Company places its proprietary nerve monitoring systems, MaXcess and surgical instrument sets with hospitals for an extended period at no up-front cost to them. The Company also offers a range of bone allograft in patented saline packaging, disposables and spine implants, which include its branded CoRoent^® products and fixation devices such as rods, plates and screws. Implants, biologics and disposables are shipped from the Company’s inventories. The Company sells an immaterial quantity of MAS instrument sets, MaXcess and nerve monitoring systems to hospitals. Basis of Presentation and Principles of Consolidation. The accompanying unaudited condensed 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. When there is a portion of equity in an acquired subsidiary not attributable, directly or indirectly, to the parent, the Company records the fair value of the noncontrolling interests at the acquisition date and classifies the amounts attributable to noncontrolling interests separately in equity in the Company’s condensed 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 condensed 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 accounting principles generally accepted in the United States ("GAAP"). Operating results for the three months ended March 31, 2014 are not necessarily indicative of the results that may be expected for any other interim period or for the full year. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2013 included in NuVasive’s Annual Report on Form 10-K filed with the SEC. In the opinion of management, the condensed consolidated financial statements include all adjustments necessary, which are of a normal and recurring nature, for the fair presentation of the Company's financial position and of the results of operations and cash flows for the periods presented. Change in Accounting Estimate. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. During the three months ended March 31, 2014, the Company completed a review of the estimated useful life of the international surgical instrument sets used in support of its business outside of the United States. Based on historical useful life information, as well as forecasted product life cycles and demand expectations, the useful life of certain international surgical instrument sets was extended from three to four years, which is consistent with the domestic depreciable lives. In accordance with authoritative guidance, this was accounted for as a change in accounting estimate and was made on a prospective basis effective January 1, 2014. For the three months ended March 31, 2014, depreciation expense, which is included in sales, marketing and administrative expenses, was approximately $0.7 million less than it would have been had the useful life of these assets not been extended. The Company expects to have a $2.8 million favorable impact to its consolidated statement of operations, for the full year ended December 31, 2014 due to this change in estimate. The total net impact to the Company's consolidated statement of operations for all four years affected by the change will be zero. Comprehensive Income (Loss). Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive income (loss) includes unrealized gains or losses on the Company’s marketable securities and foreign currency translation adjustments. The cumulative translation adjustments included in accumulated other comprehensive income (loss) were a net cumulative gain of $2.2 million and $3.3 million at March 31, 2014 and December 31, 2013, respectively. Long-Lived Assets. The Company periodically re-evaluates the original assumptions and rationale utilized in the establishment of the carrying value and estimated lives of its long-lived assets. The criteria used for these evaluations include management’s estimate of the asset’s continuing ability to generate income from operations and positive cash flow in future periods as well as the strategic significance of any intangible asset to the Company’s business objectives. If assets are considered to be impaired, the impairment recognized is the amount by which the carrying value of the assets exceeds the fair value of the assets, which is determined by applicable market prices, when available. In connection with certain restructuring activities, as further described in Note 12, Restructuring Charges, the Company wrote-off approximately $2.2 million in leasehold improvements associated with exiting a majority of the leased square footage at its New Jersey location during the three months ended March 31, 2014. Excluding these leasehold improvements write-offs, the Company did not recognize any significant impairment during the three months ended March 31, 2014. The long-lived assets balances as of March 31, 2014 and December 31, 2013 include Company owned surgical instruments, which are loaned to surgeons and hospitals who purchase implants, biologics and disposables for use in individual procedures. Inventories. The Company’s inventory consists primarily of purchased finished goods which includes specialized implants and disposables, and is stated at the lower of cost or market determined by a weighted average cost method. The Company reviews the components of its inventory on a periodic basis for excess, obsolete or impaired inventory, and records a reserve for such identified items. The inventory reserve was $22.3 million and $21.9 million at March 31, 2014 and December 31, 2013, respectively.

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 is focused on developing minimally-disruptive surgical products and procedurally-integrated solutions for the spine. NuVasive's principal product offering includes a minimally-disruptive surgical platform called "Maximum Access Surgery", or "MAS^®", as well as an offering of biologics, cervical and motion preservation products. 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 reproducible outcomes for the surgeon. The platform includes a proprietary software-driven nerve detection and avoidance systems, NVM5 and NVJJB, and Intra-Operative Monitoring ("IOM") support; MaXcess^®, an integrated split-blade retractor system; and a wide variety of specialized implants. The individual components of NuVasive's MAS platform, and many of the Company's products, can also be used in open or traditional spine surgery. The Company continues to focus significant 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 primary business model is to loan its MAS systems to surgeons and hospitals who purchase implants, biologics and disposables for use in individual procedures. In addition, for larger customers, the Company places its proprietary nerve monitoring systems, MaXcess and surgical instrument sets with hospitals for an extended period at no up-front cost to them. The Company also offers a range of bone allograft in patented saline packaging, disposables and spine implants, which include its branded CoRoent^® products and fixation devices such as rods, plates and screws. Implants, biologics and disposables are shipped from the Company’s inventories. The Company sells an immaterial quantity of MAS instrument sets, MaXcess and nerve monitoring systems to hospitals.

Basis of Presentation and Principles of Consolidation. The accompanying unaudited condensed 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. When there is a portion of equity in an acquired subsidiary not attributable, directly or indirectly, to the parent, the Company records the fair value of the noncontrolling interests at the acquisition date and classifies the amounts attributable to noncontrolling interests separately in equity in the Company’s condensed 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 condensed 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 accounting principles generally accepted in the United States ("GAAP"). Operating results for the three months ended March 31, 2014 are not necessarily indicative of the results that may be expected for any other interim period or for the full year. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2013 included in NuVasive’s Annual Report on Form 10-K filed with the SEC. In the opinion of management, the condensed consolidated financial statements include all adjustments necessary, which are of a normal and recurring nature, for the fair presentation of the Company's financial position and of the results of operations and cash flows for the periods presented.

Change in Accounting Estimate. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

During the three months ended March 31, 2014, the Company completed a review of the estimated useful life of the international surgical instrument sets used in support of its business outside of the United States. Based on historical useful life information, as well as forecasted product life cycles and demand expectations, the useful life of certain international surgical instrument sets was extended from three to four years, which is consistent with the domestic depreciable lives. In accordance with authoritative guidance, this was accounted for as a change in accounting estimate and was made on a prospective basis effective January 1, 2014. For the three months ended March 31, 2014, depreciation expense, which is included in sales, marketing and administrative expenses, was approximately $0.7 million less than it would have been had the useful life of these assets not been extended. The Company expects to have a $2.8 million favorable impact to its consolidated statement of operations, for the full year ended December 31, 2014 due to this change in estimate. The total net impact to the Company's consolidated statement of operations for all four years affected by the change will be zero.

Comprehensive Income (Loss). Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive income (loss) includes unrealized gains or losses on the Company’s marketable securities and foreign currency translation adjustments. The cumulative translation adjustments included in accumulated other comprehensive income (loss) were a net cumulative gain of $2.2 million and $3.3 million at March 31, 2014 and December 31, 2013, respectively.

Long-Lived Assets. The Company periodically re-evaluates the original assumptions and rationale utilized in the establishment of the carrying value and estimated lives of its long-lived assets. The criteria used for these evaluations include management’s estimate of the asset’s continuing ability to generate income from operations and positive cash flow in future periods as well as the strategic significance of any intangible asset to the Company’s business objectives. If assets are considered to be impaired, the impairment recognized is the amount by which the carrying value of the assets exceeds the fair value of the assets, which is determined by applicable market prices, when available. In connection with certain restructuring activities, as further described in Note 12, Restructuring Charges, the Company wrote-off approximately $2.2 million in leasehold improvements associated with exiting a majority of the leased square footage at its New Jersey location during the three months ended March 31, 2014. Excluding these leasehold improvements write-offs, the Company did not recognize any significant impairment during the three months ended March 31, 2014. The long-lived assets balances as of March 31, 2014 and December 31, 2013 include Company owned surgical instruments, which are loaned to surgeons and hospitals who purchase implants, biologics and disposables for use in individual procedures.

Inventories. The Company’s inventory consists primarily of purchased finished goods which includes specialized implants and disposables, and is stated at the lower of cost or market determined by a weighted average cost method. The Company reviews the components of its inventory on a periodic basis for excess, obsolete or impaired inventory, and records a reserve for such identified items. The inventory reserve was $22.3 million and $21.9 million at March 31, 2014 and December 31, 2013, respectively.