2.2.0.25falsefalse40308 - Disclosure - Investments (Net Realized Gains (Losses), Before Taxes) (Details)truefalseIn Millionsfalse1falsefalseUSDfalsefalse1/1/2010 - 12/31/2010 USD ($) USD ($) / shares $Duration_1_1_2010_To_12_31_2010http://www.sec.gov/CIK0000731766duration2010-01-01T00:00:002010-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit14Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2009 - 12/31/2009 USD ($) USD ($) / shares $Duration_1_1_2009_To_12_31_20092http://www.sec.gov/CIK0000731766duration2009-01-01T00:00:002009-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit14Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3falsefalseUSDfalsefalse1/1/2008 - 12/31/2008 USD ($) USD ($) / shares $Duration_1_1_2008_To_12_31_20082http://www.sec.gov/CIK0000731766duration2008-01-01T00:00:002008-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit14Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2true0us-gaap_InvestmentsAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalse3false0us-gaap_MarketableSecuritiesRealizedGainLossOtherThanTemporaryImpairmentsAmountus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-23000000-23falsetruefalsefalsefalse2truefalsefalse-64000000-64falsetruefalsefalsefalse3truefalsefalse-121000000-121falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis element represents the amount of loss recognized for other than temporary impairments of investments in debt and equity securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 falsefalse4false0unh_PortionOfImpairmentLossRecognizedInOtherComprehensiveIncomeunhfalsedebitdurationPortion of impairment loss recognized in other comprehensive income.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse00falsefalsefalsefalsefalse2truefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00  falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryPortion of impairment loss recognized in other comprehensive income.No authoritative reference available.falsefalse5false0unh_OtherThanTemporaryImpairmentLossesRecognizedInEarningsunhfalsedebitdurationOther-than-temporary impairment losses recognized in income.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse-23000000-23falsefalsefalsefalsefalse2truefalsefalse-64000000-64falsefalsefalsefalsefalse3truefalsefalse-121000000-121falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryOther-than-temporary impairment losses recognized in income.No authoritative reference available.truefalse6false0us-gaap_AvailableForSaleSecuritiesGrossRealizedLossesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-6000000-6falsefalsefalsefalsefalse2truefalsefalse-41000000-41falsefalsefalsefalsefalse3truefalsefalse-50000000-50falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 21 -Subparagraph a falsefalse7false0us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse100000000100falsefalsefalsefalsefalse2truefalsefalse116000000116falsefalsefalsefalsefalse3truefalsefalse165000000165falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 21 -Subparagraph a falsefalse8false0us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNetus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse7100000071falsetruefalsefalsefalse2truefalsefalse1100000011falsetruefalsefalsefalse3truefalsefalse-6000000-6falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments of the subject investments in debt and equity securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 truefalse37Investments (Net Realized Gains (Losses), Before Taxes) (Details) (USD $)MillionsUnKnownUnKnownUnKnownfalsetrue