2.2.0.25falsefalse002010 - Statement - CONSOLIDATED BALANCE SHEETS ParentheticaltruefalseIn Thousands, except Share datafalse1falsefalseUSDfalsefalse12/31/2010 USD ($) USD ($) / shares $c00029http://www.sec.gov/CIK0000741508instant2010-12-31T00:00:000001-01-01T00:00:00u000Standardhttp://www.xbrl.org/2003/iso4217USDiso42170u002Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0u001Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse12/31/2009 USD ($) USD ($) / shares $c00019http://www.sec.gov/CIK0000741508instant2009-12-31T00:00:000001-01-01T00:00:00u000Standardhttp://www.xbrl.org/2003/iso4217USDiso42170u001Standardhttp://www.xbrl.org/2003/instancesharesxbrli0u002Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3true0nve_ParentheticalDataForCondensedConsolidatedBalanceSheetsnvefalsenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseParenthetical Data For Consolidated Balance Sheets4false0us-gaap_AllowanceForDoubtfulAccountsReceivableCurrentus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse2868400028684falsetruefalsefalsefalse2truefalsefalse3234100032341falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryA valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 4 -Article 5 falsefalseAccounts receivable less allowance for uncollectible accounts: 2010-$28,684; 2009-$32,3415false0us-gaap_CommonStockParOrStatedValuePerShareus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse1.001.00falsetruefalsefalsefalse2truefalsefalse1.001.00falsetruefalsefalsefalseEPSus-types:perShareItemTypedecimalFace amount or stated value of common stock per share; generally not indicative of the fair market value per share.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 30 -Article 5 falsetrueCommon stock, par value6false0us-gaap_CommonStockSharesAuthorizedus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse350000000350000000falsefalsefalsefalsefalse2truefalsefalse350000000350000000falsefalsefalsefalsefalseSharesxbrli:sharesItemTypesharesThe maximum number of common shares permitted to be issued by an entity's charter and bylaws.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 30 -Article 5 falsefalseCommon stock, shares authorized7false0us-gaap_CommonStockSharesIssuedus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse235322553235322553falsefalsefalsefalsefalse2truefalsefalse234834169234834169falsefalsefalsefalsefalseSharesxbrli:sharesItemTypesharesTotal number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 30 -Article 5 falsefalseCommon stock, issued and outstanding25CONSOLIDATED BALANCE SHEETS Parenthetical (USD $)ThousandsNoRoundingNoRoundingUnKnownfalsetrue