2.2.0.25falsefalse40401 - Disclosure - Fair Value (Narrative) (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$2falsefalseUSDfalsefalse12/31/2009
USD ($)
USD ($) / shares
$As_Of_12_31_20093http://www.sec.gov/CIK0000731766instant2009-12-31T00:00:000001-01-01T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit14Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$5false0unh_FairValueMeasurementInputReconciliationOnRecurringBasisAssetsAndLiabilitiesLevel1And2TransfersNetunhfalsedebitdurationFair Value Measurement Input Reconciliation, On Recurring Basis, Assets and Liabilities, Level 1 and 2 Transfers Netfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse00falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryFair Value Measurement Input Reconciliation, On Recurring Basis, Assets and Liabilities, Level 1 and 2 Transfers NetNo authoritative reference available.falsefalse6false0us-gaap_GoodwillImpairmentLossus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse172000000172falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryLoss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph e(2)
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 43
Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 47
-Subparagraph b
Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 20
falsefalse7false0unh_FairValuesOfLevel3InvestmentsInVentureCapitalPortfoliosunhfalsedebitinstantFair values of Level 3 investments in venture capital portfoliosfalsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse166000000166falsefalsefalsefalsefalse2truefalsefalse282000000282falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryFair values of Level 3 investments in venture capital portfoliosNo authoritative reference available.falsefalse8false0unh_RemainingLevelThreePreferredStockAndOtherItemsEquitySecuritiesHoldingsunhfalsedebitinstantRemaining Level 3 preferred stock and other items equity securities holdings.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse4200000042falsetruefalsefalsefalse2truefalsefalse3000000030falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryRemaining Level 3 preferred stock and other items equity securities holdings.No authoritative reference available.falsefalse24Fair Value (Narrative) (Details) (USD $)MillionsUnKnownUnKnownUnKnownfalsetrue
