2.2.0.25truefalse0035 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)truefalsefalse1falsefalseUSDfalsefalse3/31/2011 USD ($) USD ($) / shares $I2011Q1http://www.sec.gov/CIK0000787250instant2011-03-31T00:00:000001-01-01T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse12/31/2010 USD ($) / shares USD ($) $I2010http://www.sec.gov/CIK0000787250instant2010-12-31T00:00:000001-01-01T00:00:00USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false0us-gaap_CommonStockParOrStatedValuePerShareus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse0.010.01falsetruefalsefalsefalse2truefalsefalse0.010.01falsetruefalsefalsefalseEPSus-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 value (in dollars per share)3false0us-gaap_CommonStockSharesAuthorizedus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse250000000250000000falsefalsefalsefalsefalse2truefalsefalse250000000250000000falsefalsefalsefalsefalseSharesxbrli: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 falsefalseShares authorized4false0us-gaap_CommonStockSharesIssuedus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse163724211163724211falsefalsefalsefalsefalse2truefalsefalse163724211163724211falsefalsefalsefalsefalseSharesxbrli: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 falsefalseShares issued5false0us-gaap_CommonStockSharesOutstandingus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse116931350116931350falsefalsefalsefalsefalse2truefalsefalse116924844116924844falsefalsefalsefalsefalseSharesxbrli:sharesItemTypesharesTotal number of shares of common stock held by shareholders. May be all or portion of the number of common shares authorized. These shares represent the ownership interest of the common shareholders. Excludes common shares repurchased by the entity and held as Treasury shares. Shares outstanding equals shares issued minus shares held in treasury. Does not include common shares that have been repurchased.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 30 -Article 5 falsefalseShares outstanding6false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.dplinc.com/role/balancesheetparenthetical1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalseUSDtruefalse{dei_LegalEntityAxis} : THE DAYTON POWER AND LIGHT COMPANY 3/31/2011 USD ($) USD ($) / shares $I2011Q1_SubsidiariesMemberhttp://www.sec.gov/CIK0000787250instant2011-03-31T00:00:000001-01-01T00:00:00falsefalseTHE DAYTON POWER AND LIGHT COMPANYdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_SubsidiariesMemberdei_LegalEntityAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$4falsefalseUSDtruefalse{dei_LegalEntityAxis} : THE DAYTON POWER AND LIGHT COMPANY 12/31/2010 USD ($) USD ($) / shares $I2010_SubsidiariesMemberhttp://www.sec.gov/CIK0000787250instant2010-12-31T00:00:000001-01-01T00:00:00falsefalseTHE DAYTON POWER AND LIGHT COMPANYdei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_SubsidiariesMemberdei_LegalEntityAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseTHE DAYTON POWER AND LIGHT COMPANY7false0us-gaap_CommonStockParOrStatedValuePerShareus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse0.010.01falsetruefalsefalsefalse2truefalsefalse0.010.01falsetruefalsefalsefalseEPSus-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 value (in dollars per share)26CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)UnKnownNoRoundingNoRoundingUnKnownfalsetrue