2.2.0.25falsefalse40606 - Disclosure - Investment Securities (Maturity Ranges of ARS Portfolio) (Details)truefalseIn Millions, unless otherwise specifiedfalse1falsefalseUSDfalsefalse3/31/2011
USD ($)
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available.falsefalse5false0ma_HeldToMaturityDebtMaturitiesAfterTenYearsThroughTwentyYearsParAmountmafalsedebitinstantHeld to Maturity, Debt Maturities, After Ten Years Through Twenty Years, Par Amountfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse10000001falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryHeld to Maturity, Debt Maturities, After Ten Years Through Twenty Years, Par AmountNo authoritative reference available.falsefalse6false0ma_HeldToMaturityDebtMaturitiesAfterTwentyYearsThroughThirtyYearsParAmountmafalsedebitinstantHeld to Maturity, Debt Maturities, After Twenty Years Through Thirty Years, Par Amountfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse8100000081falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryHeld to Maturity, Debt Maturities, After Twenty Years Through Thirty Years, Par AmountNo authoritative reference available.falsefalse7false0ma_HeldToMaturityDebtMaturitiesAfterThirtyYearsParAmountmafalsedebitinstantHeld to Maturity, Debt Maturities, After Thirty Years, Par Amountfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse1700000017falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryHeld to Maturity, Debt Maturities, After Thirty Years, Par AmountNo authoritative reference available.falsefalse8false0ma_HeldToMaturityDebtMaturitiesParAmountmafalsedebitinstantHeld to Maturity, Debt Maturities, Par Amountfalsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse103000000103falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryHeld to Maturity, Debt Maturities, Par AmountNo authoritative reference available.truefalse9true0ma_HeldToMaturityDebtMaturitiesPercentAbstractmafalsenadurationHeld to Maturity, Debt Maturities, Percent [Abstract]falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringHeld to Maturity, Debt Maturities, Percent [Abstract]falsefalse10false0ma_HeldToMaturityDebtMaturitiesWithinTenYearsRelativePercentFromTotalPortfoliomafalsenainstantHeld to Maturity, Debt Maturities, within Ten Years, Relative Percent From Total Portfoliofalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.040.04falsefalsefalsefalsefalseOtherus-types:percentItemTypepureHeld to Maturity, Debt Maturities, within Ten Years, Relative Percent From Total PortfolioNo authoritative reference available.falsefalse11false0ma_HeldToMaturityDebtMaturitiesAfterTenYearsThroughTwentyYearsRelativePercentFromTotalPortfoliomafalsenainstantHeld to Maturity, Debt Maturities, After Ten Years Through Twenty Years, Relative Percent From Total Portfoliofalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.010.01falsefalsefalsefalsefalseOtherus-types:percentItemTypepureHeld to Maturity, Debt Maturities, After Ten Years Through Twenty Years, Relative Percent From Total PortfolioNo authoritative reference available.falsefalse12false0ma_HeldToMaturityDebtMaturitiesAfterTwentyYearsThroughThirtyYearsRelativePercentFromTotalPortfoliomafalsenainstantHeld to Maturity, Debt Maturities, After Twenty Years Through Thirty Years, Relative Percent From Total Portfoliofalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.780.78falsefalsefalsefalsefalseOtherus-types:percentItemTypepureHeld to Maturity, Debt Maturities, After Twenty Years Through Thirty Years, Relative Percent From Total PortfolioNo authoritative reference available.falsefalse13false0ma_HeldToMaturityDebtMaturitiesAfterThirtyYearsRelativePercentFromTotalPortfoliomafalsenainstantHeld to Maturity, Debt Maturities, After Thirty Years, Relative Percent From Total Portfoliofalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.170.17falsefalsefalsefalsefalseOtherus-types:percentItemTypepureHeld to Maturity, Debt Maturities, After Thirty Years, Relative Percent From Total PortfolioNo authoritative reference available.falsefalse14false0ma_HeldToMaturityDebtMaturitiesPercentmafalsenainstantHeld to Maturity, Debt Maturities, Percentfalsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truetruefalse1.001.00falsefalsefalsefalsefalseOtherus-types:percentItemTypepureHeld to Maturity, Debt Maturities, PercentNo authoritative reference available.truefalse112Investment Securities (Maturity Ranges of ARS Portfolio) (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruetrue