1.0.0.3 false Statement Of Financial Position Unclassified - Deposit Based Operations (Parenthetical) (USD $) false 1 $ false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 shares Standard http://www.xbrl.org/2003/instance shares 0 false 2 $ false false iso4217_USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 iso4217_USD_per_shares Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 shares Standard http://www.xbrl.org/2003/instance shares 0 5 3 us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 true true 101000000000 101000000000.00 false false 2 true true 73000000000 73000000000.00 false false No definition available. No authoritative reference available. false 6 3 us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 3734000000 3734000000.00 false false 2 false true 3073000000 3073000000.00 false false No definition available. No authoritative reference available. false 7 3 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 275000000 275000000.00 false false 2 false true 208000000 208000000.00 false false No definition available. No authoritative reference available. false 8 3 us-gaap_FiniteLivedIntangibleAssetsFairValueDisclosure us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true 137000000 137000000.00 false false 2 false true 184000000 184000000.00 false false No definition available. No authoritative reference available. false 9 3 ms_ShortTermDebtAtFairValue ms false credit instant monetary Short-term Debt, at Fair Value false false false false false false false false false 1 false true 791000000 791000000.00 false false 2 false true 1246000000 1246000000.00 false false Short-term Debt, at Fair Value No authoritative reference available. false 10 3 ms_DepositsAtFairValue ms false credit instant monetary Deposits, at Fair Value false false false false false false false false false 1 false true 4967000000 4967000000.00 false false 2 false true 9993000000 9993000000.00 false false Deposits, at Fair Value No authoritative reference available. false 11 3 ms_LongTermDebtAtFairValue ms false credit instant monetary Long-term Debt, at Fair Value false false false false false false false false false 1 true true 37610000000 37610000000.00 false false 2 true true 30766000000 30766000000.00 false false Long-term Debt, at Fair Value No authoritative reference available. false 12 3 us-gaap_CommonStockParOrStatedValuePerShare us-gaap true na instant decimal No definition available. false false false false false false false false true 1 true true 0.01 0.01 false false 2 true true 0.01 0.01 false false No definition available. No authoritative reference available. false 13 3 us-gaap_CommonStockSharesAuthorized us-gaap true na instant shares No definition available. false false false false false false false false false 1 false true 3500000000 3500000000.00 false false 2 false true 3500000000 3500000000.00 false false No definition available. No authoritative reference available. false 14 3 us-gaap_CommonStockSharesIssued us-gaap true na instant shares No definition available. false false false false false false false false false 1 false true 1487850163 1487850163.00 false false 2 false true 1211701552 1211701552.00 false false No definition available. No authoritative reference available. false 15 3 us-gaap_CommonStockSharesOutstanding us-gaap true na instant shares No definition available. false false false false false false false false false 1 false true 1360595214 1360595214.00 false false 2 false true 1074497565 1074497565.00 false false No definition available. No authoritative reference available. false 16 3 us-gaap_TreasuryStockShares us-gaap true na instant shares No definition available. false false false false false false false false false 1 false true 127254949 127254949.00 false false 2 false true 137203987 137203987.00 false false No definition available. No authoritative reference available. false false 2 12 false NoRounding NoRounding Hundreds false true