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2.2.0.25truefalse40302 - Disclosure - Investments (Short-term and Long-term Investments) (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$2false0us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLossus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse60000006falsetruefalsefalsefalse2truefalsefalse80000008falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the gross unrealized losses for securities which are categorized neither as held-to-maturity nor trading securities. Such gross unrealized losses are the excess of the carrying value of the Available-for-sale Securities over their fair value as of the reporting date. Such gross unrealized losses are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 19 falsefalse3false0unh_MarketableSecuritiesAmortizedCostunhfalsedebitinstantThis item represents the cost of debt and equity securities [including held-to-maturity, trading, and available for sale],...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse1633300000016333falsefalsefalsefalsefalse2truefalsefalse1410700000014107falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the cost of debt and equity securities [including held-to-maturity, trading, and available for sale], net of adjustments made for accretion, amortization, other-than-temporary impairments, and hedging, if any.No authoritative reference available.falsefalse4false0unh_MarketableSecuritiesUnrealizedGainsunhfalsedebitinstantThis item represents the unrealized gain on debt and equity securities, including held-to-maturity, trading, and available...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse532000000532falsefalsefalsefalsefalse2truefalsefalse497000000497falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the unrealized gain on debt and equity securities, including held-to-maturity, trading, and available for sale.No authoritative reference available.falsefalse5false0unh_MarketableSecuritiesUnrealizedLossesunhfalsecreditinstantThis item represents the unrealized loss on debt and equity securities, including held-to-maturity, trading, and available...falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-81000000-81falsefalsefalsefalsefalse2truefalsefalse-50000000-50falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the unrealized loss on debt and equity securities, including held-to-maturity, trading, and available for sale.No authoritative reference available.falsefalse6false0us-gaap_MarketableSecuritiesus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse1678400000016784falsefalsefalsefalsefalse2truefalsefalse1455400000014554falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryTotal debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 19 falsefalse7false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.unitedhealthgroup.com/taxonomy/role/disclosureinvestmentsshorttermandlongterminvestmentsdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalseUSDtruefalse{us-gaap_InvestmentTypeAxis} : Available-for-sale {us-gaap_InvestmentSecondaryCategorizationAxis} : Debt Securities 1/1/2010 - 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Such gross unrealized gains are the excess of the fair value of the Available-for-sale Securities over their carrying value as of the reporting date. Such gross unrealized gains are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge. All or a portion of the unrealized holding gain of an available-for-sale security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 19 falsefalse10false0us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLossus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-67000000-67falsefalsefalsefalsefalse2truefalsefalse-36000000-36falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the gross unrealized losses for securities which are categorized neither as held-to-maturity nor trading securities. Such gross unrealized losses are the excess of the carrying value of the Available-for-sale Securities over their fair value as of the reporting date. Such gross unrealized losses are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 19 falsefalse11false0us-gaap_AvailableForSaleSecuritiesus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse1606000000016060falsefalsefalsefalsefalse2truefalsefalse1377400000013774falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryFor an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading. Such securities are reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph b Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 14 falsefalse12false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.unitedhealthgroup.com/taxonomy/role/disclosureinvestmentsshorttermandlongterminvestmentsdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse5falsefalseUSDtruefalse{us-gaap_InvestmentTypeAxis} : Available-for-sale {us-gaap_InvestmentSecondaryCategorizationAxis} : Debt Securities {us-gaap_ScheduleOfAvailableForSaleSecuritiesMajorTypesOfDebtAndEquitySecuritiesAxis} : Non-U.S. Agency Mortgage-backed Securities 1/1/2010 - 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Such gross unrealized gains are the excess of the fair value of the Available-for-sale Securities over their carrying value as of the reporting date. Such gross unrealized gains are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge. All or a portion of the unrealized holding gain of an available-for-sale security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 19 falsefalse15false0us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLossus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse00falsefalsefalsefalsefalse2truefalsefalse-5000000-5falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the gross unrealized losses for securities which are categorized neither as held-to-maturity nor trading securities. 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All or a portion of the unrealized holding loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 19 falsefalse16false0us-gaap_AvailableForSaleSecuritiesus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse465000000465falsefalsefalsefalsefalse2truefalsefalse538000000538falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryFor an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading. 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All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph b Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 14 falsefalse17false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.unitedhealthgroup.com/taxonomy/role/disclosureinvestmentsshorttermandlongterminvestmentsdetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse7falsefalseUSDtruefalse{us-gaap_InvestmentTypeAxis} : Available-for-sale {us-gaap_InvestmentSecondaryCategorizationAxis} : Debt Securities {us-gaap_ScheduleOfAvailableForSaleSecuritiesMajorTypesOfDebtAndEquitySecuritiesAxis} : U.S. Government and Agency Obligations 1/1/2010 - 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Such gross unrealized gains are the excess of the fair value of the Available-for-sale Securities over their carrying value as of the reporting date. Such gross unrealized gains are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge. All or a portion of the unrealized holding gain of an available-for-sale security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 22 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 19 falsefalse20false0us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLossus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-8000000-8falsefalsefalsefalsefalse2truefalsefalse-11000000-11falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis item represents the gross unrealized losses for securities which are categorized neither as held-to-maturity nor trading securities. 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