Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income (loss) Balance, at the beginning of period Balance, at the end of period Business acquisitions Payments to Acquire Businesses, Net of Cash Acquired Additional Paid in Capital Additional paid-in capital Surplus Stock or Unit Option Plan Expense Option expense Advances to Affiliate Advances to subsidiaries Allowance for Loan and Lease Losses [Roll Forward] Allowance for credit losses Allowance for Loan and Lease Losses, Provision for Loss, Net Total provision for credit losses Allowance for Loan and Lease Losses, Recoveries of Bad Debts Gross recoveries Recoveries Allowance for Loan and Lease Losses, Write-offs Gross credit losses Charge-offs Charge-offs Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Cash flow hedges expected to be reclassified within 12 months Ancillary Fee Income Generated by Servicing Financial Assets, Amount Ancillary fees Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Discount Rate Discount rate, transferor's continuing involvement (as a percent) Business Acquisition, Percentage of Voting Interests Acquired Percentage of share capital acquired Cash and Due from Banks Cash and due from banks at end of period Cash and due from banks at beginning of period Cash and due from banks (including segregated cash and other deposits) Cash and due from banks (including segregated cash and other deposits) Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities, Expected Credit Losses Anticipated net credit losses, date of sale or securitization (as a percent) Earnings Per Share, Basic Net income (in dollars per share) Net income (loss) (in dollars per share) Anticipated credit losses, transferor's continuing involvement (as a percent) Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Expected Credit Losses Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Prepayment Speed Constant prepayment rate, transferor's continuing involvement (as a percent) Assumption for Fair Value of Assets or Liabilities that relate to Transferor's Continuing Involvement, Weighted Average Life Weighted average life, transferor's continuing involvement (in years) Proceeds from (Repayments of) Short-term Debt Change in short-term borrowings Net change in short-term borrowings and other investment banking and brokerage borrowings-third-party Increase (Decrease) in Trading Liabilities Change in trading account liabilities Commercial Paper Commercial paper Commitments and Contingencies Disclosure [Text Block] CONTINGENCIES Common Stock, Shares Authorized Common stock, authorized shares (in shares) Common Stock, Shares, Issued Common stock, issued shares (in shares) Common Stock, Value, Issued Common stock ($0.01 par value; authorized shares: 6 billion), issued shares: 2,946,798,740 as of March 31, 2012 and 2,937,755,921 as of December 31, 2011 Capital stock ($20 par value) outstanding shares: 37,534,553 in each period Interest Paid, Net Cash paid during the year for interest Interest Compensation Related Costs, Policy [Policy Text Block] Stock-Based Compensation Comprehensive Income (Loss), Net of Tax, Attributable to Parent Citigroup's comprehensive income Comprehensive Income (Loss) Note [Text Block] CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Concentration Risk Disclosure [Text Block] CONCENTRATIONS OF CREDIT RISK Concentration Risk [Table] Contractually Specified Servicing Fees, Amount Servicing fees Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Net unrealized gains (losses) on foreign currency translation, after-tax Foreign currency translation adjustment, net of taxes Current Federal Tax Expense (Benefit) Federal Current Foreign Tax Expense (Benefit) Foreign Current Income Tax Expense (Benefit) Total current income taxes Current State and Local Tax Expense (Benefit) State Debt Disclosure [Text Block] DEBT Debt Instrument [Line Items] Long-Term Debt: Schedule of Long-term Debt Instruments [Table] Title of Individual with Relationship to Entity [Domain] Deferred Federal Income Tax Expense (Benefit) Federal Deferred Foreign Income Tax Expense (Benefit) Foreign Deferred tax benefit Deferred Income Tax Expense (Benefit) Total deferred income taxes Deferred State and Local Income Tax Expense (Benefit) State Deferred Tax Assets, Gross Gross deferred tax assets Deferred Tax Assets, Total Deferred Tax Assets, Hedging Transactions Cash flow hedges Deferred Tax Assets (Liabilities), Net Net deferred tax asset Total Amount of recognized net deferred tax asset for which realization is more likely than not Deferred Tax Assets, Net Deferred tax assets after valuation allowance Deferred Tax Assets, Operating Loss Carryforwards Net operating loss (NOL) Deferred Tax Assets, Operating Loss Carryforwards, Domestic Total U.S. separate tax returns federal NOL carryforwards Deferred Tax Assets, Other Other deferred tax assets Other Deferred tax asset recorded as a result of adoption of new accounting standards for deferred asset acquisition costs Deferred Tax Assets, Tax Credit Carryforwards, Foreign Foreign Tax Credit (FTC) U.S. foreign tax credit carryforward period Deferred Tax Assets, Tax Credit Carryforwards, General Business General Business Credits (GBC) Total U.S. consolidated tax return general business credit carryforward Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Deferred compensation and employee benefits Compensation deductions that reduced additional paid-in capital Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Provision for Loan Losses Credit loss deduction Deferred Tax Assets, Valuation Allowance Valuation allowance Deferred Tax Liabilities, Goodwill and Intangible Assets, Intangible Assets Intangibles Deferred Tax Liabilities Gross deferred tax liabilities Deferred Tax Liabilities, Other Other deferred tax liabilities Deferred Tax Liabilities, Undistributed Foreign Earnings Additional tax liability on earnings from investment of undistributed earnings of foreign subsidiaries Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability Deferred tax liabilities that will reverse in the relevant carryforward period Deferred Tax Liability Not Recognized, Cumulative Amount of Temporary Difference Deferred Tax Liability Not Recognized, Cumulative Amount of Temporary Difference Deferred Tax Liability Not Recognized, Name of Temporary Difference [Domain] Deferred Tax Liability Not Recognized [Axis] Deferred Tax Liability Not Recognized [Line Items] Deferred Tax Liability Not Recognized Deferred Tax Liability Not Recognized [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Contribution Plan, Cost Recognized Pretax expense associated with Citigroup 401(k) plan Deposits Total deposits Deposits Cash deposit Depreciation, Amortization and Accretion, Net Depreciation and amortization Derivative, Name [Domain] Derivative Asset, Fair Value, Gross Asset Derivative receivables Total Gross Derivatives, Assets Fair value, amounts receivable Derivative Liability, Fair Value, Gross Liability Derivative payables Total Gross Derivatives, Liabilities Fair value, amounts payable Derivative Assets Net receivables Total derivatives, assets Derivative, by Nature [Axis] Derivative [Member] Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] DERIVATIVES ACTIVITIES Derivative [Table] Guarantor Obligations, Current Carrying Value Carrying value Guarantor Obligations, Maximum Exposure, Undiscounted Total amount outstanding Guarantor Obligations, Nature [Domain] Guarantor Obligations by Nature [Axis] Guarantor Obligations [Line Items] Guarantor Obligations Schedule of Guarantor Obligations [Table] Earnings Per Share, Diluted Net income (in dollars per share) Net income (loss) (in dollars per share) Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] DISCONTINUED OPERATIONS Interest Income and Interest Expense Disclosure [Text Block] INTEREST REVENUE AND EXPENSE Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block] FEDERAL FUNDS/SECURITIES BORROWED, LOANED, AND SUBJECT TO REPURCHASE AGREEMENTS Consolidation, Policy [Policy Text Block] Principles of Consolidation Disposal Groups, Including Discontinued Operations, Name [Domain] Discontinued Operation, Amount of Other Income (Loss) from Disposition of Discontinued Operation, Net of Tax Loss on the sale of Student Loan Corporation, from discontinued operations After-tax gain (loss) on the sale of business Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Axis] Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Gain (loss) on sale Gain on sale Gain on sale of discontinued operations Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax Income (loss) from discontinued operations, net of taxes Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Discontinued operations Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Proceeds from Divestiture of Businesses and Interests in Affiliates Total cash value of the discontinued operation disposal transaction Cash proceeds received from disposal transaction Noncash or Part Noncash Divestitures by Unique Name [Axis] Noncash or Part Noncash Divestitures [Line Items] Noncash or Part Noncash Divestitures Noncash or Part Noncash Divestitures [Table] Due to and from Broker-Dealers and Clearing Organizations Disclosure [Text Block] BROKERAGE RECEIVABLES AND BROKERAGE PAYABLES Income (Loss) from Continuing Operations before Income Taxes, Foreign Foreign pretax earnings Income (Loss) from Equity Method Investments Equities in undistributed income of subsidiaries Equity in undistributed income of subsidiaries Effect of Exchange Rate on Cash and Cash Equivalents Effect of exchange rate changes on cash and due from banks Effective Income Tax Rate, Continuing Operations Effective income tax rate (as a percent) Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate Federal statutory rate (as a percent) Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential Foreign income tax rate differential (as a percent) Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amortization Goodwill (as a percent) Effective Income Tax Rate Reconciliation, Other Adjustments Other, net (as a percent) Effective Income Tax Rate Reconciliation, State and Local Income Taxes State income taxes, net of federal benefit (as a percent) Effective Income Tax Rate Reconciliation, Tax Exempt Income Tax advantaged investments (as a percent) Effective Income Tax Rate Reconciliation, Tax Settlements Audit settlements (as a percent) Allocated Share-based Compensation Expense Total compensation expense relating to stock-based compensation programs Expenses for deferred cash awards Recognized compensation expense related to stock award and stock option programs Equity Method Investment, Ownership Percentage Percentage of ownership in joint venture Equity method investment ownership percentage Cost-method Investments, Aggregate Carrying Amount Non-marketable equity securities carried at cost Excess Net Capital at 1500 Percent Excess over minimum requirement Policyholder Benefits and Claims Incurred, Net Policyholder benefits and claims Fair Value of Securities Received as Collateral that Can be Resold or Repledged Market value of collateral received that may be sold or repledged Federal Funds Purchased and Securities Sold under Agreements to Repurchase Federal funds purchased and securities loaned or sold under agreements to repurchase (including $137,571 and $112,770 as of March 31, 2012 and December 31, 2011, respectively, at fair value) Federal funds purchased and securities loaned or sold Federal funds purchased and securities loaned or sold under agreements to repurchase Total federal funds purchased and securities loaned or sold under agreements to repurchase Federal Funds Sold and Securities Purchased under Agreements to Resell Federal funds sold and securities borrowed or purchased under agreements to resell (including $172,435 and $142,862 as of March 31, 2012 and December 31, 2011, respectively, at fair value) Federal funds sold and resale agreements Total federal funds sold and securities borrowed or purchased under agreements to resell Federal funds sold and securities borrowed or purchased under agreements to resell Collateralized advances from Federal Home Loan Bank, long-term Long-term Federal Home Loan Bank Advances Federal Home Loan Bank, Advances, Short-term Collateralized advances from Federal Home Loan Bank, short-term Foreign Currency Transactions and Translations Policy [Policy Text Block] Foreign Currency Translation Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net Net gain (loss) excluded from assessment of the effectiveness of fair value hedges Gain (Loss) on Fair Value Hedge Ineffectiveness, Net Hedge ineffectiveness recognized in earnings on designated and qualifying fair value hedges Gain (Loss) on Securitization of Financial Assets Gains (losses) recognized on the securitization Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Goodwill Goodwill and Intangible Assets, Policy [Policy Text Block] Goodwill Goodwill [Line Items] Goodwill: Income (Loss) from Continuing Operations Attributable to Parent Income from continuing operations-excluding noncontrolling interests Income (Loss) from Continuing Operations, Per Diluted Share Income from continuing operations (in dollars per share) Income from continuing operations Income (Loss) from Continuing Operations, Per Basic Share Income from continuing operations (in dollars per share) Income from continuing operations Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Income (loss) from discontinued operations, net of taxes Income from discontinued operations, net of taxes Income (loss) from discontinued operations, net of taxes Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share Income from discontinued operations, net of taxes (in dollars per share) Discontinued operations (in dollars per share) Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share Income from discontinued operations, net of taxes (in dollars per share) Discontinued operations (in dollars per share) Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax Income (loss) from discontinued operations Income from discontinued operations Discontinued Operation, Amount of Other Income (Loss) from Disposition of Discontinued Operations, before Income Tax Pretax gain (loss) on the sale of business Discontinued Operation, Tax Effect of Discontinued Operation Provision for income taxes Provision (benefit) for income taxes Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle Provision (benefit) for income taxes on cumulative effect of accounting changes Income Tax Effects Allocated Directly to Equity, Employee Stock Options Employee stock plans Income Tax Disclosure [Text Block] INCOME TAXES Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Total interest and penalties in the consolidated statement of income, pretax Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Total interest and penalties in the consolidated balance sheet at the beginning of the period, pretax Total interest and penalties in the consolidated balance sheet at the end of the period, pretax Income Tax, Policy [Policy Text Block] Income Taxes Income Taxes Paid, Net Cash paid/(received) during the year for income taxes Income taxes Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Gain (loss) on the derivatives in designated and qualifying fair value hedges Gain (loss) on credit spread Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Gain (loss) on the hedged item in designated and qualifying fair value hedges Increase (Decrease) in Trading Securities Change in trading account assets Incremental Common Shares Attributable to Share-based Payment Arrangements Other employee plans (in shares) Incremental Common Shares Attributable to Written Put Options Options (in shares) Intangible Assets, Net (Excluding Goodwill) Intangible assets (other than MSRs) Goodwill Goodwill Balance of goodwill at beginning of period Balance of goodwill at end of period Interest-bearing Deposit Liabilities, Domestic Interest-bearing deposits in U.S. offices (including $806 and $848 as of March 31, 2012 and December 31, 2011, respectively, at fair value) Interest-bearing deposits in U.S. offices Interest-bearing Deposit Liabilities, Foreign Interest-bearing deposits in offices outside the U.S. (including $521 and $478 as of March 31, 2012 and December 31, 2011, respectively, at fair value) Interest-bearing deposits in offices outside the U.S. Interest-bearing Deposits in Banks and Other Financial Institutions Deposits with banks Interest Expense Interest expense Total interest expense Interest Expense, Deposits Deposits Total deposits Interest Expense, Federal Funds Purchased and Securities Sold under Agreements to Repurchase Federal funds purchased and securities loaned or sold under agreements to repurchase Interest Expense, Long-term Debt Long-term debt Interest Expense, Short-term Borrowings Excluding Federal Funds and Securities Sold under Agreements to Repurchase Short-term borrowings Interest Expense, Trading Liabilities Trading account liabilities Interest Income (Expense), after Provision for Loan Loss Net interest revenue after provision for loan losses Interest Income, Federal Funds Sold and Securities Purchased under Agreements to Resell Federal funds sold and securities borrowed or purchased under agreements to resell Interest Income, Deposits with Financial Institutions Deposits with banks Interest Income, Securities, Tax Exempt Interest exempt from U.S. federal income tax Interest Income, Securities, Taxable Taxable interest Other Interest and Dividend Income Other interest Interest and Dividend Income, Securities, Trading or Measured at Fair Value Trading account assets Investment, Policy [Policy Text Block] Investment Securities Investments. Investments Total investments Investments Proceeds from Issuance of Senior Long-term Debt Issuance of ADIA Upper Decs equity units purchase contract Proceeds from Issuance of Subordinated Long-term Debt Issuances of T-DECs-APIC Labor and Related Expense Compensation and benefits Late Fee Income Generated by Servicing Financial Assets, Amount Late fees Liabilities Total liabilities Total liabilities Liabilities of Disposal Group, Including Discontinued Operation Liabilities of discontinued operations held for sale Total liabilities Total liabilities at the time of sale of Nikko Cordial reflected in Citi Holdings prior to sale Liabilities and Equity Total liabilities and equity Line of Credit Facility, Amount Outstanding Amount drawn down on long-term financing facilities with unaffiliated banks Line of Credit Facility, Maximum Borrowing Capacity Uncollateralized revolving line of credit facility with unaffiliated banks, amount undrawn Interest and Fee Income, Loans and Leases Loan interest, including fees Loans and Leases Receivable, Net of Deferred Income Loans, net of unearned income Loans, net of unearned income Total loans Loans and Leases Receivable, Gross, Carrying Amount Total loans Carrying Value Leases Receivable, Gross, Commercial, Lease Financing Lease finance receivables Loans and Leases Receivable, Deferred Income Net unearned income (loss) Long-term Debt, Maturities, Repayments of Principal after Year Five Thereafter 2012 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months Long-term Debt, Maturities, Repayments of Principal in Year Five 2016 Long-term Debt, Maturities, Repayments of Principal in Year Four 2015 Long-term Debt, Maturities, Repayments of Principal in Year Three 2014 2013 Long-term Debt, Maturities, Repayments of Principal in Year Two Long-term Debt Long-term debt Total long-term debt Long-term debt Loss Contingencies by Nature of Contingency [Axis] Loss Contingencies [Line Items] Contingencies Loss Contingencies [Table] Loss Contingency, Estimate of Possible Loss Estimation of damages Loss Contingency, Nature [Domain] Available-for-sale Securities Securities available-for-sale, at fair value Fair value Held To Maturity Securities Debt securities held-to-maturity Carrying value Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit Gross uncertain tax positions for items expected to be resolved in next 12 months Maximum Length of Time Hedged in Cash Flow Hedge Maximum length of time hedged in cash flow hedge Stockholders' Equity Attributable to Noncontrolling Interest Noncontrolling interest Noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Dividends paid to noncontrolling-interest shareholders Noncontrolling Interest, Period Increase (Decrease) Net change in noncontrolling interests Noncontrolling Interest, Increase from Equity Issuance or Sale of Parent Equity Interest Initial origination of a noncontrolling interest Variable Interest Entities by Classification of Entity [Axis] Net Capital Net capital or equivalent Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash provided by operating activities of continuing operations Net cash provided by (used in) operating activities of continuing operations Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Cash flows from operating activities of continuing operations Net Cash Provided by (Used in) Discontinued Operations Net cash provided by (used in) discontinued operations Net cash provided by (used in) discontinued operations Net cash provided by (used in) discontinued operations Increase (Decrease) in Deposits Change in deposits Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net Change in federal funds purchased and securities loaned or sold under agreements to repurchase Proceeds from (Payments for) in Interest-bearing Deposits in Banks Change in deposits with banks Increase (Decrease) in Loans Held-for-sale Change in loans held-for-sale Proceeds from (Repayments of) Long-term Debt and Capital Securities Proceeds / (repayments) from issuance of long-term debt-third-party, net Net Income (Loss) Attributable to Parent Citigroup's net income Net income Citigroup's net income Net income allocated to common shareholders for basic EPS Net Income (Loss) Available to Common Stockholders, Basic Interest Income (Expense), Net Net interest revenue Loans and Leases Receivable, Allowance Allowance for loan losses Allowance for loan losses at the beginning of period Allowance for loan losses at the end of period Allowance for loan losses Total allowance for loan losses Loans and Leases Receivable, Net Reported Amount Total loans, net Total loans, net New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle New Accounting Pronouncements or Change in Accounting Principle [Table] Noninterest-bearing Deposit Liabilities, Domestic Non-interest-bearing deposits in U.S. offices Noninterest-bearing Deposit Liabilities, Foreign Non-interest-bearing deposits in offices outside the U.S. Communications and Information Technology Technology/communication Occupancy, Net Premises and equipment Other Noninterest Expense Other operating Noninterest Income Total non-interest revenues Fees and Commissions Total MSR fees Total commissions and fees Commissions and fees Gain (Loss) on Sale of Securities, Net Realized gains from sales of investments Noninterest Income, Other Other revenue Derivative gains and losses not recorded within trading activities Principal Transactions Revenue Principal transactions Principal transactions revenue Marketing and Advertising Expense Advertising and marketing Dividend Income, Operating Dividends Interest and Dividend Income, Operating Interest revenue Total interest revenue Operating Leases, Future Minimum Payments Due Future minimum annual rentals, total Operating Leases, Future Minimum Payments Due, Current 2012 Operating Leases, Future Minimum Payments, Due in Five Years 2016 Operating Leases, Future Minimum Payments, Due in Four Years 2015 Operating Leases, Future Minimum Payments, Due in Three Years 2014 Operating Leases, Future Minimum Payments, Due in Two Years 2013 Operating Leases, Future Minimum Payments, Due Thereafter Thereafter Revenues Total revenues, net of interest expense Revenues, net of interest expense Other Assets Other assets Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Pension liability adjustment, net of taxes Change in accumulated other comprehensive income (loss) Other Comprehensive Income (Loss), Minimum Pension Liability Net Adjustment, Tax Pension liability adjustments Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income (loss) Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Cash flow hedges Payments for (Proceeds from) Other Investing Activities Other investing activities Other Liabilities Other liabilities Other liabilities Proceeds from (Payments for) Other Financing Activities Other financing activities Other Short-term Borrowings Other short-term borrowings Payments of Dividends Dividends paid Pension and Other Postretirement Benefits Disclosure [Text Block] RETIREMENT BENEFITS Defined Benefit Plan, Accumulated Benefit Obligation Accumulated benefit obligation at year end Defined Benefit Plan, Actual Return on Plan Assets Actual return on plan assets Defined Benefit Plan, Actuarial Net (Gains) Losses Net actuarial loss Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter 2017-2021 Defined Benefit Plan, Amortization of Gains (Losses) Net actuarial loss Defined Benefit Plan, Amortization of Net Gains (Losses) Net actuarial loss that will be amortized from Accumulated other comprehensive income (loss) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Prior service cost (benefit) Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit) Prior service cost that will be amortized from Accumulated other comprehensive income (loss) Defined Benefit Plan, Amortization of Net Transition Asset (Obligation) Net transition obligation that will be amortized from Accumulated other comprehensive income (loss) Defined Benefit Plan, Amounts Recognized in Balance Sheet Net amount recognized on the balance sheet Funded status Defined Benefit Plan, Benefits Paid Benefits paid Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation Acquisitions Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets Acquisitions Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Change in projected benefit obligation Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Change in plan assets Defined Benefit Plan, Contributions by Employer Total contribution made by the company in 2012 Company contributions Defined Benefit Plan, Curtailments Curtailments gains Defined Benefit Plan, Debt Securities Debt securities (as a percent) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Discount rate (as a percent) Defined Benefit Plan, Divestitures, Benefit Obligation Divestitures Defined Benefit Plan, Divestitures, Plan Assets Divestitures Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation Effect on accumulated postretirement benefit obligation, decrease Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components Effect on benefits earned and interest cost, decrease Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation Effect on accumulated postretirement benefit obligation, increase Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components Effect on benefits earned and interest cost, increase Defined Benefit Plan, Equity Securities Equity securities (as a percent) Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year Estimated Future Employer Contributions in Next Fiscal Year Defined Benefit Plan, Expected Future Benefit Payments in Year One 2012 Defined Benefit Plan, Expected Future Benefit Payments in Year Two 2013 Defined Benefit Plan, Expected Future Benefit Payments in Year Three 2014 Defined Benefit Plan, Expected Future Benefit Payments in Year Four 2015 Defined Benefit Plan, Expected Future Benefit Payments in Year Five 2016 Defined Benefit Plan, Expected Return on Plan Assets Expected return on plan assets Expected returns on Plan assets Defined Benefit Plan, Fair Value of Plan Assets Plan assets at fair value at beginning of year Plan assets at fair value at year end Total assets Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Benefit Obligation Foreign exchange impact and other Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets Foreign exchange impact Defined Benefit Plan, Funded Status of Plan Funded status of the plan at year end Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year Following year (as a percent) Defined Benefit Plan, Interest Cost Interest cost on benefit obligation Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax Net actuarial loss Defined Benefit Plan, Net Periodic Benefit Cost Total net (benefit) expense Defined Benefit Plan, Other Plan Assets Other investments (as a percent) Defined Benefit Plan, Plan Amendments Plan amendments Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax Prior service cost (benefit) Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Benefit Obligation Projected benefit obligation Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Future compensation increase rate (as a percent) Defined Benefit Plan, Real Estate Real estate (as a percent) Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments Curtailment (gain) loss Defined Benefit Plan, Service Cost Benefits earned during the period Defined Benefit Plan, Settlements, Benefit Obligation Settlements Defined Benefit Plan, Settlements, Plan Assets Settlements Defined Benefit Plan, Special Termination Benefits Special termination costs Specia/contractual termination benefits Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Transition Assets (Obligations), before Tax Net transition obligation Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Ultimate rate to which cost increase is assume to decline (as a percent) Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate Year in which the ultimate rate is reached Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plan, Benefit Obligation Projected benefit obligation at beginning of year Projected benefit obligation at year end Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure Schedule of Defined Benefit Plans Disclosures [Table] Preferred Stock, Shares Authorized Preferred stock, authorized shares (in shares) Preferred Stock, Shares Issued Preferred stock, issued shares, at aggregate liquidation value (in shares) Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Prescription Drug Benefit, Effect of Subsidy on Net Periodic Postretirement Benefit Cost Reduction in postretirement expense due to subsidy received Prescription Drug Benefit, Reduction in Accumulated Postretirement Benefit Obligation for Subsidy Reduction in accumulated postretirement benefit obligation due to subsidy received Prescription Drug Subsidy Receipts, Five Fiscal Years Thereafter 2016-2020 Prescription Drug Subsidy Receipts, Year One 2011 Prescription Drug Subsidy Receipts, Year Two 2012 Prescription Drug Subsidy Receipts, Year Three 2013 Prescription Drug Subsidy Receipts, Year Four 2014 Prescription Drug Subsidy Receipts, Year Five 2015 Proceeds from Contributions from Parent Capital contributions from parent Proceeds from Issuance of Common Stock Issuance of common stock Proceeds from Issuance of Preferred Stock and Preference Stock Issuance of preferred stock Proceeds from Issuance of Long-term Debt Issuance of long-term debt Proceeds from Maturities, Prepayments and Calls of Other Investments Proceeds from maturities of investments Proceeds from Sale of Productive Assets Proceeds from sales of premises and equipment, subsidiaries and affiliates, and repossessed assets Proceeds from Sale of Other Investments Proceeds from sales of investments Proceeds from Sale of Loans and Leases Held-for-investment Proceeds from sales and securitizations of loans Proceeds from sales of loans Property, Plant and Equipment, Net Premises and equipment, net Provision for Loan, Lease, and Other Losses Provision for credit losses Provision for Loan Losses Expensed Provision for loan losses Payments to Acquire Investments Purchases of investments Payments to Acquire Loans Held-for-investment Change in loans Payments to Acquire Property, Plant, and Equipment Capital expenditures on premises and equipment and capitalized software Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together by Type [Axis] LOANS Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Roll-forward of company's unrecognized tax benefits Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities Payments and redemptions of long-term debt Payments for Repurchase of Common Stock Treasury stock acquired Restructuring Charges Restructuring Retained Earnings (Accumulated Deficit) Retained earnings Premiums Earned, Net Insurance premiums Revenue Recognition, Policy [Policy Text Block] Commissions, Underwriting and Principal Transactions Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-Term Debt Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block] Summarized financial information for Combined Results of Discontinued Operations Schedule of Goodwill [Table Text Block] Changes in Goodwill by segment Schedule of Short-term Debt [Text Block] Schedule of Short-Term Borrowings Schedule of Servicing Assets at Fair Value [Table Text Block] Schedule of changes in capitalized MSRs Securities Received as Collateral Securities and other marketable assets held as collateral, the majority of which collateral is held to reimburse losses realized under securities lending indemnifications Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together, Principal Amount Outstanding Principal amount of loans and other financial instruments Financial Instruments Owned and Pledged as Collateral, Amount Not Eligible to be Repledged by Counterparty Amount of collateral pledged with secured parties that may not be sold or repledged Segment Reporting Disclosure [Text Block] BUSINESS SEGMENTS Schedule of Segment Reporting Information, by Segment [Table Text Block] Information regarding the Company's operations by segment Segment Reporting Information [Line Items] Segment reporting information Schedule of Segment Reporting Information, by Segment [Table] Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Discount Rate Carrying value of retained interests, impact of 10% adverse change in discount rate Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Expected Credit Losses Carrying value of retained interests, impact of 10% adverse change in anticipated net credit losses Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Prepayment Speed Carrying value of retained interests, impact of 10% adverse change in constant prepayment rate Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 20 Percent Adverse Change in Discount Rate Carrying value of retained interests, impact of 20% adverse change in discount rate Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 20 Percent Adverse Change in Expected Credit Losses Carrying value of retained interests, impact of 20% adverse change in anticipated net credit losses Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 20 Percent Adverse Change in Prepayment Speed Carrying value of retained interests, impact of 20% adverse change in constant prepayment rate Servicing Asset at Fair Value, Additions Originations Servicing Asset at Fair Value, Amount Balance at beginning of period Balance at end of period Mortgage servicing rights (MSRs) Servicing Asset at Fair Value, Changes in Fair Value Resulting from Changes in Valuation Inputs or Changes in Assumptions Changes in fair value of MSRs due to changes in inputs and assumptions Schedule of Servicing Assets at Fair Value [Table] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Cancelled awards (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value Cancelled awards (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Shares granted as equity awards Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value New awards (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Unvested at the beginning of the period (in shares) Unvested at the end of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Unvested at the beginning of the period (in dollars per share) Unvested at the end of the period (in dollars per share) Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Unrecognized compensation cost of unvested stock awards Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition Weighted-average period of recognition of unrecognized compensation cost of unvested stock awards (in years) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Shares issued as immediately-vested stock payments (in shares) Vested awards (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Vested awards (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date Tenure of award (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Award vesting period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights Vesting rights Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Number of shares authorized for grant (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Number of shares available for grant/purchase (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Exercised (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period Expired (in options) Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Expired (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Forfeited or exchanged (in options) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Forfeited or exchanged (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period Granted-original (in options) Stock options granted to certain employees (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures Strike price of options (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-average per-share fair value at the end of the period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Outstanding at the beginning of the period (in options) Outstanding at the end of the period (in options) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Antidilutive options, weighted average exercise price (in dollars per share) Outstanding at the beginning of the period (in dollars per share) Outstanding at the end of the period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Exercisable at end of period (in options) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Exercisable at end of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected dividend yield (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Weighted-average expected life, Original grants (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Expected volatility (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Risk-free interest rate (as a percent) Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Incentive Plans Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Short-term Debt, Weighted Average Interest Rate Weighted average (as a percent) Short-term Debt [Line Items] Short-Term Borrowings: Schedule of Short-term Debt [Table] Short-term Borrowings Total short-term borrowings Short-term borrowings Short-term borrowings Class of Warrant or Right, Exercise Price of Warrants or Rights Antidilutive securities weighted average exercise price (in dollars per share) Subsequent Event Type [Axis] Subsequent Event [Line Items] Subsequent Event Subsequent Event [Table] Subsequent Event Type [Domain] Goodwill and Intangible Assets Disclosure [Text Block] GOODWILL AND INTANGIBLE ASSETS Summary of Income Tax Contingencies [Text Block] Roll-forward of the company's unrecognized tax benefits Tax Credit Carryforward, Valuation Allowance Tax carry-forward valuation allowance Tier One Leverage Capital Required for Capital Adequacy to Average Assets Required minimum leverage ratio (as a percent) Tier One Leverage Capital Required to be Well Capitalized to Average Assets Well-capitalized minimum leverage ratio (as a percent) Tier One Leverage Capital to Average Assets Leverage ratio (as a percent) Tier One Risk Based Capital Tier 1 Capital Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Required minimum tier 1 capital ratio (as a percent) Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets Well-capitalized minimum tier 1 capital ratio (as a percent) Tier One Risk Based Capital to Risk Weighted Assets Tier 1 Capital ratio (as a percent) Capital Total Capital Capital Required for Capital Adequacy to Risk Weighted Assets Required minimum total capital ratio (as a percent) Capital Required to be Well Capitalized to Risk Weighted Assets Well-capitalized minimum total capital ratio (as a percent) Capital to Risk Weighted Assets Total Capital ratio (as a percent) Trading Liabilities Trading account liabilities Trading account liabilities Transfers and Servicing of Financial Assets, Policy [Text Block] Transfers of Financial Assets Unrecognized Tax Benefits Total unrecognized tax benefits at the beginning of the period Total unrecognized tax benefits at the end of the period Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations Reductions due to lapse of statutes of limitations Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions Gross amount of decreases for prior years' tax positions Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities Amounts of decreases relating to settlements Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions Net amount of increase for current years' tax positions Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions Gross amount of increases for prior years' tax positions Unrecognized Tax Benefits that Would Impact Effective Tax Rate Amount of unrecognized tax benefit which would impact effective tax rate if recognized. Use of Estimates Use of Estimates Schedule of Variable Interest Entities [Text Block] Schedule of consolidated and unconsolidated VIEs with which the Company holds significant variable interests Schedule of Variable Interest Entities [Table] Variable Interest Entity [Line Items] Variable Interest Entity Weighted Average Number of Shares Outstanding, Diluted Adjusted weighted-average common shares outstanding applicable to diluted EPS Adjusted weighted average common shares outstanding Weighted Average Number of Shares Outstanding, Basic Weighted-average common shares outstanding applicable to basic EPS (in shares) Weighted average common shares outstanding (in shares) Available-for-sale Securities [Table Text Block] Amortized cost and fair value of securities available-for-sale Schedule of Available-for-sale Securities [Table] Available-for-sale Securities, Amortized Cost Basis Amortized cost Total amortized cost Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis Due within 1 year, amortized cost Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Basis After 1 but within 5 years, amortized cost Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis After 5 but within 10 years, amortized cost Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis After 10 years, amortized cost Available-for-sale Securities, Debt Maturities, Amortized Cost Basis Total amortized cost Available-for-sale Securities, Debt Maturities, within One Year, Fair Value Fair value, due within 1 year Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value Fair value, after 1 but within 5 years Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value Fair value, after 5 but within 10 years Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Fair value, after 10 years Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Fair value of available for sale securities that have been in an unrealized loss position for less than twelve months Available-for-sale investments in a gross-unrealized-loss position for less than twelve months Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Fair value of available for sale securities that have been in an unrealized loss position for twelve months or longer Fixed income investments in a gross unrealized loss position for twelve months or longer Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Total fair value of available for sale securities that have been in an unrealized loss position Held-to-maturity Securities [Table Text Block] Carrying value and fair value of debt securities held-to-maturity (HTM) Schedule of Held-to-maturity Securities [Table] Held To Maturity Securities Fair Value Fair value Held-to-maturity Securities, Debt Maturities, within One Year, Fair Value Due within 1 year, fair value Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Fair Value After 1 but within 5 years, fair value Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Fair Value After 5 but within 10 years, fair value Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value After 10 years, fair value Held-to-maturity Securities, Debt Maturities, Fair Value Total fair value Held-to-maturity Securities, Sold Security, at Carrying Value Carrying value of held-to-maturity investments sold Investments held-to-maturity sold Held-to-maturity Securities, Sold Security, Realized Gain (Loss) Loss realized on sale of held to maturity securities Net pretax loss recognized in the consolidated statement of income Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Fair value less than 12 months Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Fair value 12 months or longer Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value Fair value, total Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses Gross unrecognized losses less than 12 months Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses Gross unrecognized losses 12 months or longer Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses Gross unrecognized losses, total Assets Total assets Identifiable assets Receivable Type [Domain] Trading Securities Trading account assets Trading account assets Trading account assets Intangible Assets Disclosure [Text Block] Components of intangible assets Investment Income [Table Text Block] Interest and dividends on investments Types of Financial Instruments [Domain] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] INCENTIVE PLANS Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, Disclosure Item Amounts [Domain] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions. Scenario, Unspecified [Domain] Statement [Table] Statement, Scenario [Axis] Antidilutive Securities, Name [Domain] Investments, Fair Value Disclosure Investments, at fair value Investments Loans Receivable, Fair Value Disclosure Loans Loans at fair value Loans held at fair value Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure Federal funds sold and securities borrowed or purchased under agreements to resell, at fair value Federal funds sold and securities borrowed or purchased under agreements to resell, selected portfolios of securities purchased under agreements to resell and securities borrowed Federal funds sold and securities borrowed or purchased under agreements to resell Trading Liabilities, Fair Value Disclosure Trading account liabilities Statement Statement [Line Items] Transferor's Interests in Transferred Financial Assets, Fair Value Carrying value of retained interests Servicing Asset at Fair Value, Amount [Roll Forward] Re-securitizations Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Balance at beginning of period, asset Balance at end of period, asset Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, Sales, Issuances, Settlements Purchases, issuances and settlements, assets Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Transfers in and/or out of Level 3, assets Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset, Period Increase (Decrease) Increase (decrease) in Level 3 asset balance during period Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair value, assets measured on recurring basis, level 3 fair-value category reconciliation Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair value, liabilities measured on recurring basis, level 3 fair-value category reconciliation Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, Sales, Issuances, Settlements Purchases, issuances and settlements, liabilities Items measured at fair value of a nonrecurring basis Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Table Text Block] Fair Value, Option [Text Block] FAIR VALUE ELECTIONS Fair Value, Option, Eligible Item or Group [Domain] Fair Value, Option, Quantitative Disclosures [Table] Fair Value, Option, Quantitative Disclosures, by Eligible Item or Group [Axis] Fair Value, Option, Quantitative Disclosures [Line Items] Fair Value Option Quantitative Disclosures Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net Transfers in and/or out of Level 3, liabilities Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability, Period Increase (Decrease) Increase (decrease) in Level 3 liability balance during period Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Discount rate (as a percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Expected long-term rate of return on assets (as a percent) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Future compensation increase rate (as a percent) Fair Value, Option, Loans Held as Assets, Aggregate Difference Aggregate unpaid principal balance in excess of fair value for non-accrual loans or loans more than 90 days past due Fair Value, Option, Credit Risk, Gains (Losses) on Assets Changes in fair value due to instrument-specific credit risk gain (loss) Fair Value, Option, Credit Risk, Gains (Losses) on Liabilities Gain (loss) on change in estimated fair value of debt liabilities due to change in company's own credit risk Quarterly Financial Information [Text Block] SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets Fair value of plan assets Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation Accumulated benefit obligation Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets Fair value of plan assets Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Cash flows from investing activities of continuing operations Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Cash flows from financing activities of continuing operations Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash used in investing activities of continuing operations Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by financing activities of continuing operations Cash Provided by (Used in) Operating Activities, Discontinued Operations Cash flows from operating activities Cash Provided by (Used in) Investing Activities, Discontinued Operations Cash flows from investing activities Cash Provided by (Used in) Financing Activities, Discontinued Operations Cash flows from financing activities Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation Projected benefit obligation Treasury Stock, Value Treasury stock, at cost: March 31, 2012-14,641,287 shares and December 31, 2011-13,877,688 shares Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Net unrealized gains (losses) on cash flow hedges, after-tax Cash flow hedges, net of taxes Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Net unrealized gains (losses) on investment securities, after-tax Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax Pension liability adjustments, after-tax Pension liability adjustment, net of taxes Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity Stockholders' Equity, Period Increase (Decrease) Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax Net amount recognized in equity-pretax Goodwill [Roll Forward] Goodwill Operating Expenses Total operating expenses Operating expenses Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities excluded from computation of earnings per common share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, by Antidilutive Securities [Axis] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Earnings Per Share, Policy [Policy Text Block] Earnings per Share Increase (Decrease) in Broker-Dealer Related Receivables (Payables), Net Change in brokerage receivables net of brokerage payables Loss Contingency, Range of Possible Loss, Portion Not Accrued Possible loss, high end of the range Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income from continuing operations before income taxes Income (loss) before taxes and equity in undistributed income of subsidiaries Income (loss) from continuing operations before income taxes Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities Schedule of Held-to-maturity Securities [Line Items] Schedule of Held-to-maturity Securities Parent Company [Member] Citigroup Parent Company Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Treasury Stock, Shares Treasury stock, shares (in shares) Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Foreign currency translation Other Comprehensive Income (Loss), Available-for-sale Securities, Tax Securities available-for-sale Deferred Compensation Arrangement with Individual, Share-based Payments, by Title of Individual [Axis] Debt, Policy [Policy Text Block] Debt Servicing Asset at Fair Value, Other Changes that Affect Balance Other changes Stockholders' Equity Attributable to Parent Total Citigroup stockholders' equity Total Citibank stockholder's equity Citigroup stockholders' equity Income Tax Expense (Benefit), Intraperiod Tax Allocation Income taxes before noncontrolling interests Income Tax Expense (Benefit) Provision for income taxes Provision (benefit) for income taxes Income taxes (benefits) Provision (benefit) for income taxes Trading Securities Pledged as Collateral Trading account assets, pledged to creditors Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount Due within 1 year, carrying value Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount After 1 but within 5 years, carrying value Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount After 5 but within 10 years, carrying value Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount After 10 years, carrying value Held-to-maturity Securities, Debt Maturities, Net Carrying Amount Total carrying value Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Regulatory capital requirement Preferred Stock, Value, Issued Preferred stock ($1.00 par value; authorized shares: 30 million), issued shares: 12,038 as of March 31, 2012 and December 31, 2011, at aggregate liquidation value Carrying value at the end of the year US Government Agencies Debt Securities [Member] Agency obligations U.S. Agency Derivative Liabilities Net payables Total derivatives, liabilities Other Income Other income Marketable Securities, Gain (Loss) Other-than-temporary impairment losses on investments (For the three months ended June 30, 2009, gross impairment losses were $1,379 of which $631 was recognized in AOCI.) Derivative Financial Instruments, Assets [Member] Derivatives, assets Trading Account Assets [Member] Trading account assets Retained Interest [Member] Retained interests from asset securitizations Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell [Member] Federal funds sold and securities borrowed or purchased under agreements to resell Trading Liabilities [Member] Trading account liabilities Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] Federal funds purchased and securities loaned or sold under agreements to repurchase Derivative Financial Instruments, Liabilities [Member] Derivatives, liabilities Securities Sold, Not yet Purchased [Member] Securities sold, not yet purchased Defined Benefit Plan, Actual Plan Asset Allocations Total (as a percent) Statement, Equity Components [Axis] Retained earnings Retained Earnings [Member] Accumulated Net Unrealized Investment Gain (Loss) [Member] Net unrealized gains (losses) on investment securities Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss) [Member] Accumulated Translation Adjustment [Member] Foreign currency translation adjustment, net of hedges Equity Component [Domain] Equity Component [Domain] Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] Cash flow hedges Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust Junior subordinated debentures owned by statutory business trusts Stock Issued During Period, Value, Acquisitions Issuance of shares for Nikko Cordial acquisition Stock Issued During Period, Value, Conversion of Convertible Securities Conversion of preferred stock to common stock Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Employee benefit plans (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Conversion of preferred stock to common stock (in shares) Treasury Stock, Shares, Acquired Treasury stock acquired (in shares) Common stock and additional paid-in capital Common Stock Including Additional Paid in Capital [Member] Stock Issued During Period, Shares, Period Increase (Decrease) Statement, Business Segments [Axis] Segment, Geographical [Domain] Statement, Geographical [Axis] Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] U.S. government-sponsored agency guaranteed Mortgage-backed Securities, Issued by Private Enterprises [Member] Non-agency-sponsored mortgages Privately sponsored securities Net income allocated to common shareholders for diluted EPS Net Income (Loss) Available to Common Stockholders, Diluted Add: Interest expense, net of tax, on convertible securities and adjustment of undistributed earnings allocated to employee restricted and deferred shares with nonforfeitable rights to dividends, applicable to diluted EPS Dilutive Securities, Effect on Basic Earnings Per Share Stock Redeemed or Called During Period, Value Redemption or retirement of preferred stock Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Non-cash investing activities Variable Interest Entity, Classification [Domain] Treasury Stock, Value, Acquired, Cost Method Treasury stock acquired Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Options Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward] Unvested stock awards, shares Marketable Securities, Realized Loss, Other than Temporary Impairments, Amount Gross impairment losses Total impairment losses recognized in earnings Available-for-sale Securities, Fair Value Disclosure Fair Value Stock Redeemed or Called During Period, Shares Redemption or retirement of preferred stock (in shares) Other Assets, Fair Value Disclosure Other assets, at fair value Nontrading derivatives and other financial assets measured on a recurring basis Other assets Other financial assets Dividends, Common Stock Common dividends Dividends, Preferred Stock Preferred dividends Less: Preferred dividends Noncash or Part Noncash Divestiture, Name [Domain] Payments for Software Capitalized software costs Earnings Per Share [Text Block] EARNINGS PER SHARE Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income before attribution of noncontrolling interests Citigroup's net income (loss) Net income Net income before attribution of noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to noncontrolling interests Net income attributable to noncontrolling-interest shareholders Net income (loss) attributable to noncontrolling interests Net income attributable to noncontrolling-interest shareholders Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest Income from continuing operations Income (loss) from continuing operations Income from continuing operations before attribution of noncontrolling interests Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest Less: Noncontrolling interests from continuing operations Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest Less: Noncontrolling interests from discontinuing operations Accounts, Notes, Loans and Financing Receivable by Receivable Type [Axis] Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Total comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income (loss) attributable to the noncontrolling interests Total comprehensive income attributable to noncontrolling interests Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Balance, beginning of year Balance, end of period Total equity Adjustment to opening balance, net of taxes Hedging Relationship [Domain] Noncontrolling interest Noncontrolling Interest [Member] Citigroup stockholders' equity Parent [Member] Disclosure of Credit Derivatives [Table Text Block] Credit derivative portfolio Schedule of Credit Derivatives [Table] Credit Derivatives by Contract Type [Axis] Credit Derivatives Contract Type [Domain] Structured Finance [Member] Structured notes Internal Credit Rating [Member] Not rated Credit Derivatives [Line Items] Credit Derivative Credit Derivative, Maximum Exposure, Undiscounted Maximum potential amount of future payments Credit Derivative, Current Fair Value Fair value payable Other [Member] Other Credit Rating [Domain] Commercial Mortgage Backed Securities [Member] Commercial Collateralized Debt Obligations [Member] Collateralized debt obligations (CDOs) Collateralized Loan Obligations [Member] Collateralized loan obligations (CLOs) Collateralized Credit Card Securities [Member] Credit card securitizations Collateralized Auto Loans [Member] Auto loan securitizations Acquired Finite-lived Intangible Asset, Weighted Average Useful Life Weighted-average amortization period for additions in other intangibles Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities Total adjustments Defined Benefit Plan, Target Allocation Percentage of Assets, Debt Securities Debt securities, weighted-average target asset allocation (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Debt Securities, Range Minimum Debt securities, target asset allocation minimum range (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Debt Securities, Range Maximum Debt securities, target asset allocation maximum range (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities Equity securities, weighted-average target asset allocation (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities, Range Minimum Equity securities, target asset allocation minimum range (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Equity Securities, Range Maximum Equity securities, target asset allocation maximum range (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Real Estate Real estate, weighted-average target asset allocation (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Real Estate, Range Minimum Real estate, target asset allocation minimum range (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Real Estate, Range Maximum Real estate, target asset allocation maximum range (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Other, Range Minimum Other investments, target asset allocation minimum range (as a percent) Defined Benefit Plan, Target Allocation Percentage of Assets, Other, Range Maximum Other investments, target asset allocation maximum range (as a percent) Long-term Debt, Type [Axis] Available-for-sale Securities [Member] Total securities AFS AFS debt securities Held-to-maturity Securities [Member] Held-to-maturity Securities HTM debt securities Loans held for investment External Credit Rating, Investment Grade [Member] Investment grade External Credit Rating, Non Investment Grade [Member] Non-investment grade Accrued Liabilities Accrued taxes and other expenses Due to Related Parties Advances from subsidiaries Long-term Debt, Type [Domain] Defined Benefit Plan by Plan Asset Categories [Axis] Plan Asset Categories [Domain] Real Estate [Member] Real estate Defined Benefit Plan, Fair Value of Plan Assets by Measurement [Axis] Fair Value Plan Asset Measurement [Domain] Defined Benefit Plan, Transfers Between Measurement Levels Transfers in and/or out of Level 3 Defined Benefit Plan, Target Allocation Percentage of Assets, Other Other investments, weighted-average target asset allocation (as a percent) Defined Benefit Plan, Assets for Plan Benefits Benefit asset Pension and Other Postretirement Defined Benefit Plans, Liabilities Benefit liability Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Employee benefit plans Defined Benefit Plan, Purchases, Sales, and Settlements Purchases, sales, and issuances Stockholders' Equity, Other Other Investment Holdings [Line Items] Investment Holdings Investment Owned, Balance [Abstract] Investments in Alternative Investment Funds Investment Type [Axis] Investment Holdings [Table] Other than Securities Investment [Member] Other Total Return Swap [Member] Total return swaps and other Private Equity Funds [Member] Private equity funds Hedge Funds [Member] Hedge funds Schedule of Investments [Line Items] Schedule of Investments disclosures Derivatives, Fair Value, by Balance Sheet Location [Axis] Balance Sheet Location [Domain] Other Assets [Member] Other assets Other Liabilities [Member] Other liabilities Derivatives, Fair Value [Line Items] Derivative Mark-to-Market (MTM) Receivables/Payables Interest Rate Contract [Member] Interest rate contracts Foreign Exchange Contract [Member] Foreign exchange contracts Equity Contract [Member] Equity contracts Credit Risk Contract [Member] Credit derivatives Not Designated as Hedging Instrument [Member] Other derivative instruments Management hedges Derivative, Net Liability Position, Aggregate Fair Value Fair value of derivative in liability position Collateral Already Posted, Aggregate Fair Value Fair value of collateral already posted Additional Collateral, Aggregate Fair Value Additional collateral posted Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block] Gains (losses) on fair value hedges Derivative Instruments, Gain (Loss) [Line Items] Derivative gain (loss) Derivative Instruments, Gain (Loss) by Hedging Relationship [Axis] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] CONSOLIDATED STATEMENT OF CASH FLOWS CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY Stockholders' Equity Attributable to Parent [Abstract] Citibank stockholder's equity Supplemental Cash Flow Information [Abstract] Supplemental disclosure of cash flow information for continuing operations Operating Expenses [Abstract] Operating expenses Basic earnings per share Earnings Per Share, Basic [Abstract] Earnings per share Basic Diluted earnings per share Earnings Per Share, Diluted [Abstract] Earnings per share Diluted Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Stockholders' equity Derivative Contract Type [Domain] Other Trading [Member] Other trading securities Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Derivative Mark-to-Market (MTM) Receivables/Payables Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] CONSOLIDATED BALANCE SHEET CONSOLIDATED STATEMENT OF INCOME Liabilities [Abstract] Liabilities Loans and Leases Receivable, Net of Deferred Income [Abstract] Loans, net of unearned income Loans, net of unearned income: Revenues [Abstract] Revenues Trading Account Assets Pledged to Creditors This item represents marketable and other securities categorized as trading securities as of the balance sheet date and pledged to creditors. Trading account assets, pledged to creditors Provisions for Credit Losses and for Benefits and Claims, Total Total allowance for consumer and corporate credit losses primarily related to U.S. mortgages, revolving credit, and installment loans net of revolving credit and installment loan recoveries. Total provisions for credit losses and for benefits and claims Provisions for credit losses and for benefits and claims Pretax provisions (credits) for credit losses and for benefits and claims Increase (Decrease) in Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell Change in federal funds sold and securities borrowed or purchased under agreements to resell. Change in federal funds sold and securities borrowed or purchased under agreements to resell Investments, pledged to creditors Investments pledged to creditors as of the balance sheet date. Investments Pledged to Creditors Loans Receivable Consumer, Fair Value Disclosure Consumer loans, at fair value Consumer loans receivables, at fair value, as of balance sheet date. Loans Receivable Commercial, Fair Value Disclosure Commercial loans receivable, at fair value, as of balance sheet date. Corporate loans, at fair value Mortgage Servicing Rights M S R The amount of mortgage servicing rights (MSRs) as of the balance sheet date. Net carrying amount of MSRs, balance at beginning of period Net carrying amount of MSRs, balance at end of period Transfers to Repossessed Assets Transfer to repossessed assets. Transfers to OREO and other repossessed assets Transfers to repossessed assets Commissions and Fees [Text Block] Disclosure relating to commission fee revenue earned by the entity. COMMISSIONS AND FEES Trading Account Assets and Liabilities [Text Block] This element represents the complete disclosure, including tables and data, of trading account assets and liabilities, at fair value at the reporting date. TRADING ACCOUNT ASSETS AND LIABILITIES Securitizations and Variable Interest Entities [Text Block] Disclosure related to the entity's use of special purpose entities, its variable interest entities and securitizations. SECURITIZATIONS AND VARIABLE INTEREST ENTITIES Document and Entity Information Increase (Decrease) from Transactions Between Consolidating Entity and Noncontrolling Interest Shareholders Represents the amount of decrease (increase) in noncontrolling-interest on transaction with noncontrolling-interest holders. Transactions between Citigroup and the noncontrolling-interest shareholders Reset of Convertible Preferred Stock, Conversion Price Reset of convertible preferred stock at conversion price. Reset of convertible preferred stock conversion price Impact of the conversion price reset related to the $12.5 billion convertible preferred stock private issuance Intangible Assets, Excluding Mortgage Servicing Rights Sum of the carrying amounts of all intangible assets, excluding goodwill and excluding mortgage servicing rights, as of the balance sheet date, net of accumulated amortization and impairment charges. Net carrying amount of Intangible assets (excluding MSRs), balance at beginning of period Net carrying amount of Intangible assets (excluding MSRs), balance at end of period Provision for Unfunded Lending Commitments Reflects the balance sheet side of the amount charged against earnings during the period for credit losses related to unfunded lending commitments. Provision for unfunded lending commitments Provision (release) for unfunded lending commitments Common Shareholders' Equity [Member] The amount of stockholders equity attributable to common shareholders. Citigroup common stockholders' equity For investments that the entity does not intend to sell nor will likely be required to sell, the amount which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, the amount recognized in other comprehensive income. Other Comprehensive Income Reclassification before Tax Less: Impairments recognized in OCI Less: portion of OTTI loss recognized in AOCI (before taxes) Discontinued Operation Gain (Loss) On Disposal Of Discontinued Operation Net Of Tax Cash Flow Impact Gain (loss) on sale, net of taxes This element represents gain (loss) on sale of discontinued operations affecting cash flows during the period. Common Stock Issued During Period, Value Issuance of new common stock Value of common stock issued during the period. Preferred Stock Issued During Period, Value Issuance of new preferred stock Value of preferred stock issued during the period. Transfers To Trading Account Assets From Held To Maturity Investments Transfers to trading account assets from investments (held-to-maturity) Value of investments transferred to trading account assets from held-to-maturity category in noncash transactions. Transfers To Available For Sale Investments From Trading Account Assets Transfers to trading account assets from investments (available-for-sale) Value of investments transferred from trading account assets to available-for-sale category in noncash transactions. Principal Transactions [Text Block] PRINCIPAL TRANSACTIONS Disclosure of revenue by reporting categories or types of financial instruments, including derivatives but excluding dividends and interests, from trading. Preferred Stock Issued During Period, Shares Issuance of new preferred stock (in shares) Shares of preferred stock issued during the period. Common Stock Issued During Period, Shares Issuance of new common stock (in shares) The number of common shares issued during the period. Stock Issued During Period, Value Acquisition Two Issuance of shares for Grupo Cuscatlan acquisition Value of stock issued pursuant to acquisitions during the period. Stock Issued During Period, Value Acquisition Three Issuance of shares for ATD acquisition Value of stock issued pursuant to acquisitions during the period. Stock Issued During Period, Shares Acquisition Two Issuance of shares for Grupo Cuscatlan acquisition (in shares) Number of stock issued pursuant to acquisitions during the period. Stock Issued During Period, Shares Acquisition Three Issuance of shares for ATD acquisition (in shares) Number of stock issued pursuant to acquisitions during the period. Issuance of shares for Nikko Cordial acquisition Stock Issued During Period, Value Acquisition One Value of stock issued pursuant to acquisitions during the period. Stock Issued During Period, Shares Acquisition One Issuance of shares for Nikko Cordial acquisition (in shares) Number of stock issued during the period for acquisition TRADING ACCOUNT ASSETS AND LIABILITIES SECURITIZATIONS AND VARIABLE INTEREST ENTITIES FAIR VALUE ELECTIONS FEDERAL FUNDS/SECURITIES BORROWED, LOANED, AND SUBJECT TO REPURCHASE AGREEMENTS ALLOWANCE FOR CREDIT LOSSES Equity Units Purchase Contract Value of stock issued during the period for Equity units purchase contract. ADIA Upper DECs Equity Units Purchase Contract Sales of Primerica Sales of Holdings Value of stock issued during the period from Sales of holdings. Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Discontinued operations Assets [Abstract] Assets Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by (used in) operating activities of continuing operations Net Cash Provided by (Used in) Discontinued Operations [Abstract] Discontinued operations Condensed Consolidating Statements of Income: Condensed Consolidating Statement of Income [Line Items] Dividend Income Operating from Affiliates Subsidiaries and Holding Companies Dividends from subsidiaries Dividends received from subsidiary companies. Intercompany interest revenue. Interest revenue-intercompany Interest Income Operating from Affiliates Subsidiaries and Holding Company Interest Expense Operating to Affiliates Subsidiaries and Holding Company Interest expense-intercompany Intercompany interest expense. Fees and Commissions from Affiliates Subsidiaries and Holding Company Commissions and fees-intercompany Represents commissions and fees received from affiliates, subsidiaries or the holding company during the period. Principal Transactions Revenue from Affiliates Subsidiaries and Holding Company Principal transactions-intercompany Represents the net gain or loss, both realized and unrealized, arising from principal trading and principal investments received from the affiliates, subsidiaries or the holding company during the period. Citigroup Global Markets Holdings Inc [Member] Citigroup guarantees various debt obligations of CGMHI as well as all of the outstanding debt obligations under CGMHI's publicly issued debt. Citigroup Global Markets Holdings Inc. (CGMHI) Citigroup Funding, Inc. [Member] CFI is a first-tier subsidiary of Citigroup, which issues commercial paper, medium-term notes and structured equity-linked and credit-linked notes, all of which are guaranteed by Citigroup. Citigroup Funding Inc. (CFI) Citi Financial Credit Company [Member] An indirect wholly owned subsidiary of Citigroup. CCC is a wholly owned subsidiary of Associates. Citigroup has issued a full and unconditional guarantee of the outstanding indebtedness of CCC. CitiFinancial Credit Company (CCC) Associates First Capital Corporation [Member] A wholly owned subsidiary of Citigroup. Citigroup has issued a full and unconditional guarantee of the outstanding long-term debt securities and commercial paper of Associates. In addition, Citigroup guaranteed various debt obligations of Citigroup Finance Canada Inc. (CFCI), a wholly owned subsidiary of Associates. CFCI continues to issue debt in the Canadian market supported by a Citigroup guarantee. Associates are the immediate parent company of CCC. Associates Other Citigroup Subsidiaries Eliminations [Member] Includes all other subsidiaries of Citigroup, intercompany eliminations, and income/loss from discontinued operations. Other Citigroup Subsidiaries and eliminations Other Citigroup Subsidiaries, eliminations and income from discontinued operations Other Income from Affiliates Subsidiaries and Holding Company Other income-intercompany Intercompany other income. Labor and Related Expense to Affiliates Subsidiaries and Holding Company Compensation and benefits-intercompany Intercompany compensation and benefits. Other Expense Other expense The amount of expenditures towards occupancy of premises and equipment, technology and communication, advertising and marketing, restructuring and other operating expenses. Other Expense to Affiliates Subsidiaries and Holding Company Other expense-intercompany Intercompany other expense. Cash and Due from Banks Due from Affiliates Subsidiaries and Holding Companies Cash and due from banks-intercompany Represents the portion of cash on hand and due from banks of the affiliates, subsidiaries and the holding company. Federal Funds Sold and Securities Purchased under Agreements to Resell of Affiliates Subsidiaries and Holding Companies Federal funds sold and resale agreements-intercompany Represents the portion of federal funds sold and resale agreements of the affiliates, subsidiaries and the holding company. Trading Securities Due from Affiliates Subsidiaries and Holding Companies Trading account assets-intercompany Represents the portion of trading securities of the affiliates, subsidiaries and the holding company. Loans and Leases Receivable, Net of Deferred Income Due from Affiliates Subsidiaries and Holding Companies Loans, net of unearned income-intercompany Represents the portion of loans and leases receivable, net of deferred income of the affiliates, subsidiaries and the holding company. Investments in Subsidiaries Investments in subsidiaries Represents the investments in subsidiaries of the reporting entity. Other Assets, Including Deposits Brokerage Receivables Goodwill and Other Class of Assets Other assets Represents the other assets, which include deposits with banks, brokerage receivables, goodwill, intangible assets (other than MSRs), mortgage servicing rights and other assets. Other Assets, Including Deposits Brokerage Receivables Goodwill and Other Class of Assets Due from Affiliates Subsidiaries and Holding Companies Other assets-intercompany Represents the other assets, which includes deposits with banks, brokerage receivables, goodwill, intangible assets (other than MSRs), mortgage servicing rights and other assets of the affiliates, subsidiaries and the holding company as of the balance sheet date. Other liabilities-intercompany Represents other liabilities including brokerage payables of the affiliates, subsidiaries and the holding company. Other Liabilities, Including Brokerage Payables of Affiliates Subsidiaries and Holding Companies Proceeds from Payments of Investments of Affiliates Subsidiaries and Holding Companies Changes in investments and advances-intercompany Represents the intercompany changes in investments and advances during the period. Payments of Dividends to Affiliates Subsidiaries and Holding Companies Dividends paid-intercompany Represents the dividends paid to affiliates, subsidiaries and holding companies. Proceeds From Repayments Of Long Term Debt And Capital Securities Of Affiliates Subsidiaries And Holding Companies Proceeds / (repayments) from issuance of long-term debt-intercompany, net The net cash inflow (outflow) associated with security instrument that either represents a creditor or an ownership relationship with the holder of the investment security with a maturity of beyond one year or normal operating cycle, if longer of affiliates, subsidiaries and holding companies. Condensed Consolidating Statement of Cash Flows [Line Items] Condensed Consolidating Statements of Cash Flows: Cash paid during the year for: Cash Paid During the Year for [Abstract] Cash and Due from Banks Cash Flow Impact Cash and due from banks at beginning of period Cash and due from banks at end of period For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks. Federal Funds Purchased and Securities Sold under Agreements to Repurchase of Affiliates Subsidiaries and Holding Companies Federal funds purchased and securities loaned or sold-intercompany Represents the portion of federal funds purchased and securities loaned or sold of the affiliates, subsidiaries and the holding company. Trading Liabilities of Affiliates Subsidiaries and Holding Companies Trading account liabilities-intercompany Represents the trading account liabilities of the affiliates, subsidiaries and the holding company. Long Term Debt Of Affiliates Subsidiaries And Holding Companies Long-term debt-intercompany Represents the long-term debt of the affiliates, subsidiaries and the holding company. Other Liabilities, Including Brokerage Payables Other liabilities Represents other liabilities including brokerage payables of the reporting entity as of the balance sheet date. Amortization of unrecognized Defined Benefit Plan Amortization [Abstract] Commodity and Other Contract [Member] Derivative instrument whose primary underlying risk is tied to commodity prices, as well as any other derivative contract not defined elsewhere in the taxonomy. Primarily includes revenues from crude oil, refined oil products, natural gas, and other commodities trades. Commodity and other contracts Proceeds From Repayments Of Short Term Debt Of Affiliates Subsidiaries And Holding Companies Net change in short-term borrowings and other advances-intercompany This element represents proceeds from (repayment of) short-term debt of affiliates, subsidiaries and holding companies. Condensed Consolidating Balance Sheet: Condensed Consolidating Balance Sheet [Line Items] Liabilities and Equity [Abstract] Liabilities and equity Short Term Borrowings Of Affiliates Subsidiaries And Holding Companies Short-term borrowings-intercompany This element represents the short-term borrowings of affiliates, subsidiaries and holding companies. Futures and Forward [Member] Contracts negotiated between two parties to purchase and sell a specific quantity of a financial instrument, foreign currency, or commodity at a price specified at origination of the contract, with delivery and settlement at a specified future date. Futures are similar to forward contracts except that they are standardized contracts traded on an organized exchange. Futures and forwards Written Options [Member] The sale or writing of contracts to another party that convey rights, but not obligations, to buy or sell a specific commodity, or financial or equity instrument, at a specified price during a specified period or at a specified date for which a premium is received. Written options Purchased Options [Member] The purchase of contracts from another party that convey rights, but not obligations, to buy or sell a specific commodity, or financial or equity instrument, at a specified price during a specified period or at a specified date for which a premium is received. Purchased options Credit Protection Sold [Member] The party assuming the credit risk associated with the reference asset without directly purchasing the asset from another party. Protection sold Credit derivatives sold Credit Protection Purchased [Member] The party transferring the credit risk of a reference asset to another party. Protection purchased Credit derivatives purchased Derivative Asset Counterparty Netting and Market Value Adjustment Less: Netting agreements and market value adjustments to assets The sum of the amount of netting of derivative exposures covered by a qualifying master netting agreement and market adjustments (if any) related to derivative assets. Netting agreements and market value adjustments to assets Derivative Liability Counterparty Netting and Market Value Adjustment Less: Netting agreements and market value adjustments to liabilities The sum of the amount of netting of derivative exposures covered by a qualifying master netting agreement and market adjustments (if any) related to derivative liabilities. Netting agreements and market value adjustments to liabilities Netting agreements and market value adjustments to liabilities Effect of Fair Value Hedges on Results of Operations [Abstract] Gain (loss) on fair value hedges Credit Derivatives by Industry Counterparty [Axis] Credit derivatives by industry or counterparty to the risk transfer. Credit Derivatives Industry Counterparty [Domain] Classification of industry or counterparty to credit derivatives of the entity. Bank [Member] This element represents the banking industry. Bank Broker Dealer [Member] This element represents the broker-dealer sector. Broker-dealer Monoline [Member] This element represents the Monoline insurance companies. Monoline Non Financial [Member] This element represents the nonfinancial industries. Non-financial Insurance and Other Financial Institutions [Member] This element represents the general insurance companies and other financial institutions. Insurance and other financial institutions Credit Default Swaps and Options [Member] A credit default swap is a contract in which, for a fee, a protection seller agrees to reimburse a protection buyer for any losses that occur due to a credit event on a reference entity. A credit option is a credit derivative that allows investors to trade or hedge changes in the credit quality of the reference asset. Credit default swaps and options Credit Derivative Maturity [Domain] Different maturity periods to credit derivatives of the entity. Credit Derivative by Maturity [Axis] Credit derivative by maturity period. Credit Derivative Maturity within One Year [Member] This element represents the credit derivatives maturing within one year. Within 1 year Credit Derivative Maturity from One to Five Years [Member] This element represents the credit derivatives maturing between one and five years. From 1 to 5 years Credit Derivative Maturity after Five Years [Member] This element represents the credit derivatives maturing after five years. After 5 years Income (Loss) from Continuing Operation after Noncontrolling Interest Net income from continuing operations (for EPS purposes) The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent prior to adjustment for discontinued operations. Income (Loss) Available to Common Stockholders Net income available to common shareholders This element represents net income available to common shareholders before allocation to participating securities. Income Allocated to Participating Securities This element represents income allocated to participating securities. Dividends and undistributed earnings allocated to participating securities Incremental Common Shares Attributable to Tangible Equity Units TDECs (in shares) This element represents the incremental common shares attributable to tangible equity units (T-DECs), which are considered as dilutive for the purposes of computing diluted earnings per share. Convertible securities (in shares) This element represents the incremental common shares attributable to convertible securities, which are considered as dilutive for the purposes of computing diluted earnings per share. Incremental Common Shares Attributable to Convertible Securities Weighted Average Number Diluted Shares Outstanding Adjustment [Abstract] Effect of dilutive securities Citicorp Segment [Member] This element represents the Citicorp business segment. Citicorp Regional Consumer Banking [Member] This element represents the Regional Consumer Banking business segment. Regional Consumer Banking Institutional Clients Group [Member] This element represents the Institutional Clients Group business segment. Institutional Clients Group Citi Holdings Segment [Member] This element represents the Citi Holdings business segment. Citi Holdings Corporate and Other [Member] This element represents the Corporate and other segment. Corporate/Other North America [Member] This element represents the North America geographic segment. In North America Offices North America Europe Middle East Africa [Member] This element represents the geographic segment of the entity consisting of Europe, the Middle East, and Africa (EMEA). EMEA Latin America [Member] This element represents the Latin America geographic segment. Latin America Asia [Member] This element represents the Asia geographic segment. Asia Interest and Dividend Income, Operating [Abstract] Interest revenue Insurance Fees and Charges Insurance fees and charges The insurance fees and other charges paid for deposits. Interest Expense [Abstract] Interest expense Convertible Equity Units [Member] This element represents incremental common shares attributable to convertible equity units that were not included in the computation of diluted earnings per share (EPS) Equity units convertible into common stock held by the Abu Dhabi Investment Authority (ADIA) Cumulative Equity Method Investment Ownership Percentage Cumulative percentage of ownership interest held in LQIF classified as equity method investment This element represents the equity method ownership interest, after the increase in stake in the investee company. Aggregate Exercise Price of Call Option One Aggregate exercise price of option one The exercise (or strike) price stated in the contract. The fixed price at which the call option holder can purchase or purchased the underlying security one. Aggregate Exercise Price of Call Option Two Aggregate exercise price of option two The exercise (or strike) price stated in the contract. The fixed price at which the call option holder can purchase or purchased the underlying security two. Percentage of economic interest acquired in Banco de Chile Percentage of Economic Interest Acquired This element represents the percentage of economic interest acquired. Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Assets. Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Liabilities; Local Consumer Lending [Member] This element represents the local consumer lending business segment. Local Consumer Lending Brokerage and Asset Management [Member] This element represents the brokerage and asset management business segment. Brokerage and Asset Management Special Asset Pool [Member] This element represents the special asset pool business segment. Special Asset Pool Schedule of Trading Account Assets and Liabilities [Table] This element represents the summarization of information regarding trading account assets and liabilities at fair value as on the reporting date. Trading account assets and Trading account liabilities Schedule of Trading Account Assets and Liabilities [Line Items] Prime [Member] Debt securities collateralized by real estate mortgage loans (mortgages) that are classified as prime mortgages. Prime Alt A [Member] Debt securities collateralized by real estate mortgage loans (mortgages) that are classified as Alt-A mortgages (the risk profile falls between prime and subprime). Alt-A Subprime [Member] Debt securities collateralized by real estate mortgage loans (mortgages) that are classified as subprime mortgages. Subprime Non U S Residential [Member] Debt securities collateralized by real estate mortgage loans (mortgages) that are classified as non-US residential mortgages. Non-U.S. residential Commercial [Member] This element represents the investments in commercial securities. Commercial Commercial real estate Schedule of Goodwill by Reporting Unit and Segment [Table] This element represents the schedule of goodwill by reporting units and by business segments. Reporting Unit [Axis] This element represents the summarization of information relating to reportable units of the entity. North America Regional Consumer Banking [Member] This element represents the North American Regional Consumer Banking reporting unit of the entity. North America Regional Consumer Banking Europe Middle East Africa Regional Consumer Banking [Member] This element represents the Regional Consumer Banking reporting unit of the entity consisting of Europe, the Middle East, and Africa (EMEA). EMEA Regional Consumer Banking Asia Regional Consumer Banking [Member] This element represents the Asian Regional Consumer Banking reporting unit of the entity. Asia Regional Consumer Banking Latin America Regional Consumer Banking [Member] This element represents the Latin American Regional Consumer Banking reporting unit of the entity. Latin America Regional Consumer Banking Securities and Banking [Member] This element represents the Securities and Banking reporting unit of the entity. Securities and Banking Transaction Services [Member] This element represents the Transaction Services reporting unit of the entity. Transaction Services Global Transaction Services Broker and Asset Management [Member] This element represents the Brokerage and Asset Management reporting unit of the entity. Brokerage and Asset Management Local Consumer Lending Credit Card Receivables [Member] This element represents the Local Consumer Lending-Cards reporting unit of the entity. Local Consumer Lending-Cards Schedule of Goodwill by Reporting Unit [Table Text Block] Goodwill by reporting units Schedule of data about goodwill by reporting unit. Schedule of Changes in Intangible Assets [Table Text Block] Changes in intangible assets Schedule of changes in intangible assets. Reporting Unit [Domain] This element represents the reportable units of the entity. Goodwill Acquisitions Divestitures Purchase Accounting Adjustments and Other Smaller acquisitions/divestitures and other This element represents the net changes to the recorded value of goodwill due to acquisitions or divestitures, purchase accounting adjustments and other adjustments needed to revise the carrying amount of goodwill. Fair Value of Goodwill as Percentage of Allocated Book Value This element represents the fair value of goodwill as a percentage of allocated book value. Fair value as a percentage of allocated book value Schedule Of Finite And Indefinite Lived Intangible Assets By Major Class [Table] This element represents the disclosure of intangible assets excluding goodwill by major class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of the company. Finite And Indefinite Lived Intangible Assets By Major Class [Axis] This element represents the details of finite and indefinite - lived intangible assets. Finite And Indefinite Lived Intangible Assets [Domain] This element represents the details of finite and indefinite - lived intangible assets. Purchased Credit Card Relationships [Member] This element represents the value of the entity's purchased credit card relationships. Purchased credit card relationships Other Customer Relationships [Member] The intangible asset representing the value of the entity's customer relationships, not otherwise defined. Other customer relationships Present Value of Future Profits [Member] The intangible asset representing the value of the entity's present value of future profits. Present value of future profits Indefinite Lived Intangible Assets [Member] This element represents indefinite-lived intangible assets of the entity. Indefinite-lived intangible assets Other Finite Lived Intangible Assets [Member] This element represents other finite-lived intangible assets not otherwise defined in the taxonomy. Other: Finite and indefinite-lived intangible assets. Finite And Indefinite Lived Intangible Assets [Line Items] Finite and indefinite-lived intangible assets: Finite And Indefinite Lived Intangible Assets [Roll Forward] Intangible Assets, Excluding Mortgage Servicing Rights Gross Carrying Amount Gross carrying amount of Intangible assets (excluding MSRs) This element represents the gross carrying amounts of all intangible assets, excluding goodwill and mortgage servicing rights (MSRs), as of the balance sheet date. Intangible Assets, Excluding Mortgage Servicing Rights Accumulated Amortization Accumulated amortization of Intangible assets (excluding MSRs) This element represents the accumulated amortization of all intangible assets, excluding goodwill and mortgage servicing rights (MSRs), as of the balance sheet date. Mortgage Servicing Rights M S R Gross Carrying Amount Gross carrying amount of Mortgage servicing rights (MSRs) This element represents the gross carrying amount of mortgage servicing rights (MSRs) as of the balance sheet date. Intangible Assets Including Mortgage Servicing Rights Gross Carrying Amount Gross carrying amount of Intangible assets This element represents the gross carrying amount of intangible assets excluding goodwill but including mortgage servicing rights (MSRs), as of the balance sheet date. Intangible Assets, Including Mortgage Servicing Rights Accumulated Amortization Accumulated amortization of Intangible assets This element represents the accumulated amortization of all intangible assets excluding goodwill but including mortgage servicing rights (MSRs), as of the balance sheet date. Intangible Assets, Including Mortgage Servicing Rights Net carrying amount of Intangible assets, balance at beginning of period Net carrying amount of Intangible assets, balance at end of period This element represents the sum of the carrying amounts of all intangible assets excluding goodwill but including mortgage servicing rights, as of the balance sheet date that is net of accumulated amortization and impairment charges. Intangible Assets, Excluding Mortgage Servicing Rights Acquisitions Divestitures Acquisitions/divestitures This element represents the aggregate amount of intangible assets excluding mortgage servicing rights (MSRs), acquired or divested during the period. Intangible Assets, Excluding Mortgage Servicing Rights Amortization of Intangible Assets Amortization This element represents the aggregate amount of amortization of intangible assets excluding mortgage servicing rights (MSRs) during the period. Intangible Assets, Excluding Mortgage Servicing Rights Impairments Impairments This element represents the aggregate amount of impairment of intangible assets excluding mortgage servicing rights (MSRs) during the period. Intangible Assets, Excluding Mortgage Servicing Rights Translation and Purchase Accounting Adjustments FX and other This element represents net changes to the recorded value of intangible assets excluding mortgage servicing rights (MSRs), due to foreign currency translation adjustments and purchase accounting adjustments. Letters of Credit Hedged by Credit Default Swaps or Participation Notes Related to Trading Account Assets [Member] Represents the selected letters of credit hedged by credit default swaps or participation notes categorized as trading account assets. Selected letters of credit hedged by credit default swaps or participation notes (Trading account assets) Certain Trading Account Asset Related Credit Products [Member] Represents certain credit products of the reporting entity categorized as trading account assets. Certain credit products (Trading account assets) Certain Trading Account Asset Related Hybrid Financial Instruments [Member] Represents certain hybrid financial instruments of the reporting entity categorized as trading account assets. Certain hybrid financial instruments (Trading account assets) Certain Investments in Private Equity and Real Estate Ventures [Member] Represents certain investments in private equity and real estate ventures of the reporting entity. Certain investments in private equity and real estate ventures Certain Loan Related Credit Products [Member] Represents certain credit products of the reporting entity categorized as loans receivable. Certain credit products (Loans) Certain Corporate Loans [Member] Represents certain corporate loan receivable of the reporting entity. Corporate loans VIE Corporate loans Certain Consumer Loans [Member] Represents certain consumer loans receivable of the reporting entity. Consumer loans VIE Consumer loans Certain Loan Related Hybrid Financial Instruments [Member] Represents certain hybrid financial instruments of the reporting entity categorized as loans receivable. Certain hybrid financial instruments (Loans) Mortgage Servicing Rights [Member] Represents mortgage servicing rights of the reporting entity. Mortgage servicing rights Certain Mortgage Loans [Member] Represents certain mortgage loans of the reporting entity. Certain mortgage loans (HFS) Certain mortgage loans (long-term debts) Certain Equity Method Investments [Member] Represents certain equity method investments of the reporting entity. Certain equity method investments Certain Structured Liabilities Related to Interest Bearing Deposits [Member] Represents certain structured liabilities of the reporting entity categorized as interest bearing deposits. Certain structured liabilities (Interest-bearing deposits) Certain Interest Bearing Deposits Related Hybrid Financial Instruments [Member] Represents hybrid financial instruments related to interest bearing deposits of the reporting entity. Certain hybrid financial instruments (Interest-bearing deposits) Letters of Credit Hedged by Credit Default Swaps or Participation Notes Related to Trading Account Liabilities [Member] Represents the selected letters of credit hedged by credit default swaps or participation notes categorized as trading account liabilities. Selected letters of credit hedged by credit default swaps or participation notes (Trading account liabilities) Certain Trading Account Liabilities Related Hybrid Financial Instruments [Member] Represents certain hybrid financial instruments of the reporting entity categorized as trading account liabilities. Certain hybrid financial instruments (Trading account liabilities) Certain Noncollateralized Short Term Borrowings [Member] Represents certain noncollateralized short-term borrowings of the reporting entity. Certain noncollateralized short-term borrowings Certain Hybrid Financial Instruments Related To Short Term Borrowings [Member] Represents certain hybrid financial instruments of the reporting entity categorized as short-term borrowings. Certain hybrid financial instruments (Short-term borrowings) Certain Structured Liabilities Related To Short Term Borrowings [Member] Represents certain structured liabilities of the reporting entity categorized as short-term borrowings. Certain structured liabilities (Short-term borrowings) Certain Non Structured Liabilities Related To Short Term Borrowings [Member] Represents certain non-structured liabilities of the reporting entity categorized as short-term borrowings. Short-term borrowings: Certain Structured Liabilities Related To Long Term Borrowings [Member] Represents certain structured liabilities of the reporting entity categorized as long-term borrowings. Certain structured liabilities (Long-term borrowings) Certain Non Structured Liabilities Related To Long Term Borrowings [Member] Represents certain non-structured liabilities of the reporting entity categorized as long-term borrowings. Long-term debt: Certain Hybrid Financial Instruments Related To Long Term Borrowings [Member] Represents certain hybrid financial instruments of the reporting entity categorized as long-term borrowings. Certain hybrid financial instruments (Long-term borrowings) Fair Value Option Changes in Fair Value Gain (Loss) on Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell The amount of gains and losses from fair value changes in Federal funds sold and securities borrowed or purchased under agreements to resell, which are elected under fair value option, included in earnings during the period. Federal funds sold and securities borrowed or purchased under agreements to resell, selected portfolios of securities purchased under agreements to resell and securities borrowed The amount of gains and losses from fair value changes in trading account assets, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Trading Account Assets Trading account assets The amount of gains and losses from fair value changes in investments, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Investments Investments Total liabilities elected under fair value option This element represents the fair value of total liabilities for which it has been opted to apply fair value measurement for financial reporting purposes. Liabilities Elected under Fair Value Option The amount of gains and losses from fair value changes in liabilities, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Liabilities Fair value option changes in fair value gain (loss) on liabilities Aggregate notional amount of unfunded letters of credit. Notional Amount of Unfunded Letters of Credit Notional amount of unfunded letters of credit Carrying amount of unfunded loan commitments related to certain credit related products selected for fair value accounting. Unfunded Loan Receivables Commitments Outstanding Unfunded loan commitments outstanding, certain credit related products Carrying Amount of Certain Credit Related Loans Carrying amount of certain credit related trading assets as of the balance sheet date for which the fair value option was elected. Carrying amount reported on the Consolidated Balance Sheet The amount of gains and losses from fair value changes in loans receivable, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Loans Receivable Loans The amount of gains and losses from fair value changes in other assets, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Other Assets Other assets This element represents the fair value of total assets for which it has been opted to apply fair value measurement for financial reporting purposes. Assets Elected under Fair Value Option Total assets elected under fair value option Long-term debt The amount of gains and losses from fair value changes in long-term borrowings, at fair value, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes In Fair Value Gain Loss On Long Term Borrowings Schedule of Financial Instruments Selected for Fair Value Accounting [Table Text Block] Schedule of financial instruments selected for fair value accounting Represents the schedule of financial instruments along with their fair value positions, selected for fair value accounting. Also includes disclosure of the gains (losses) related to the change in fair value during the period. Represents the schedule of fair value of loans and other disclosures for certain credit related products. Schedule of fair value of loans and other disclosures for certain credit related products Schedule of Fair Value of Loans and Other Disclosures for Certain Credit Products [Table Text Block] Schedule of Fair Value of Loans and Other Disclosures for Certain Mortgage Loans [Table Text Block] Schedule of fair value of loans and other disclosures for certain mortgage loans Represents the schedule of fair value of loans and other disclosures for certain mortgage loans. The amount of gains and losses from fair value changes in assets, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Assets Total assets Changes in fair value gain (loss) on assets The amount of gains and losses from fair value changes in interest bearing deposit liabilities, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Interest Bearing Deposit Liabilities Interest-bearing deposits The amount of gains and losses from fair value changes in Federal funds purchased and securities loaned or sold under agreements to repurchase, at fair value, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Federal Funds Purchased and Securities Loaned or Sold under Agreement to Repurchase Federal funds purchased and securities loaned or sold under agreements to repurchase Selected portfolios of securities sold under agreements to repurchase and securities loaned The amount of gains and losses from fair value changes in trading account liabilities, at fair value, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes in Fair Value Gain (Loss) on Trading Account Liabilities Trading account liabilities The amount of gains and losses from fair value changes in short-term borrowings, at fair value, which are elected under fair value option, included in earnings during the period. Fair Value Option Changes In Fair Value Gain Loss On Short Term Borrowings Short-term borrowings Condensed Consolidating Statement of Income [Table Text Block] Condensed Consolidating Statements of Income Text block that encapsulates the detailed table comprising the condensed consolidating statement of income. Text block that encapsulates the detailed table comprising the condensed consolidating balance sheet. Condensed Consolidating Balance Sheet Condensed Consolidating Statement of Balance Sheet [Table Text Block] Condensed Consolidating Statement of Cash Flows [Table Text Block] Condensed Consolidating Statements of Cash Flows Text block that encapsulates the detailed table comprising the condensed consolidating statement of cash flows. Fair Value Liabilities Unfunded Lending Commitments This element represents the estimated fair value of unfunded lending commitments. This does not include the value of those commitments which are generally cancellable by providing notice to the borrower. Estimated fair values of corporate unfunded lending commitments Schedule of trading account assets and liabilities, at fair value as of the reporting date. Trading Account Assets Liabilities [Table Text Block] Trading account assets and liabilities Incremental Impact of Adopting SFAS 166 and 167 on Assets and Resulting Risk Weighted Assets [Table Text Block] The table showing the incremental impact of adopting SFAS 166/167 on GAAP assets and resulting risk-weighted assets for VIEs and former QSPEs that were consolidated or deconsolidated for accounting purposes. Incremental Impact of Adopting SFAS 166 and 167 on GAAP Assets and Resulting Risk Weighted Assets Incremental Impact of Adopting SFAS 166 and 167 on Assets, Liabilities and Stockholders' Equity [Table Text Block] The table showing the incremental impact of adopting SFAS 166/167 on GAAP assets, liabilities and stockholders' equity. Incremental Impact of Adopting SFAS 166 and 167 on GAAP Assets, Liabilities and Stockholders' Equity Mutual fund deferred sales commissions Deferred sales commissions from mutual fund. Mutual Fund Deferred Sales Commissions [Member] Equity-linked notes. Equity Linked Notes [Member] Equity linked notes This element represents the balance sheet line items. Balance Sheet Line Item [Domain] Incremental Effect of New Accounting Pronouncement on Assets The incremental increase (decrease) in assets resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Incremental effect of adopting SFAS 166/167 on assets Incremental Effect of New Accounting Pronouncement or Change in Accounting Principle on Risk Weighted Assets The incremental increase (decrease) in risk-weighted assets resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Incremental effect of adopting SFAS 166/167 on risk-weighted assets Incremental Effect of New Accounting Pronouncement or Change in Accounting Principle on Risk Weighted Assets from Consolidation The incremental increase (decrease) in risk-weighted assets from consolidation resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Incremental effect of adopting SFAS 166/167 on risk-weighted assets from consolidation Incremental Effect of New Accounting Pronouncement on Liabilities and Stockholders' Equity The incremental increase (decrease) in liabilities and stockholders' equity resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Incremental effect of adopting SFAS 166/167 on liabilities and stockholders' equity Incremental Effects on Balance Sheet Line Item [Axis] This element may be used to represent the incremental effect on balance sheet line items due to the adoption of a new accounting pronouncement. Number Of Approaches For Consolidating V I Es And Former Q S P Es The number of approaches employed by the entity for newly consolidating certain VIEs and former QSPEs. Number of approaches used for newly consolidating VIEs and former QSPEs Credit card assets. Credit Card [Member] Credit cards Student loan assets. Student Loans [Member] Student loans Municipal tender option bond assets. Municipal Tender Option Bonds [Member] Municipal tender option bonds Cumulative effect of adopting SFAS 166/167 on establishment of loan loss reserves and the reversal of residual interests held Retained Earnings Cumulative Effect of Adoption of New Accounting Standards before Tax Cumulative effect of initial adoption of new accounting standard on beginning retained earnings, before tax. Private Label Consumer Mortgages [Member] Private label consumer mortgage assets. Private label consumer mortgages Student Loan Securitizations [Member] This element represents the loans offered to individuals to assist in payment of the costs of higher education or qualifying vocational and professional schools which are securitized. Student loan securitizations Entity Administered Asset Backed Commercial Paper Conduit [Member] This element represents entity-administered asset-backed commercial paper conduits. Citi-administered asset-backed commercial paper conduits (ABCP) Incremental Effect of New Accounting Pronouncement on Liabilities The incremental increase (decrease) in liabilities resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Incremental effect of adopting SFAS 166/167 on liabilities Net Increase in Risk Weighted Assets, New Accounting Pronouncement The net increase in risk-weighted assets resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Net increase in risk-weighted assets from adoption of SFAS 166/167 Loan Loss Reserves Reduction of Risk Weighted Assets, New Accounting Pronouncement The deduction from gross risk-weighted assets due to loan loss reserves recognized as the result of the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Loan loss reserves deducted from gross risk-weighted assets from adoption of SFAS 166/167 Percentage of Loan Loss Reserves Percentage limit on loan loss reserves includable in Tier 2 capital. Percentage limit on loan loss reserves includable in Tier 2 capital Commercial Paper Third Party Conduit [Member] This element represents the third-party commercial paper conduits. Third-party commercial paper conduits Client Intermediation [Member] This element represents a range of transactions (including credit-linked and equity-linked notes) designed to provide specified returns based on the underlying security, referenced asset or index to the investors. Client intermediation Investment Funds [Member] This element represents company's investment funds that invest in various asset classes including private equity, hedge funds, real estate, fixed income and infrastructure for which it earns management fee. Investment funds This element represents the maximum funded exposure to loss in a significant unconsolidated variable interest entity, related to debt investments. Variable Interest Entity Debt Investments Funded Maximum Exposure to Loss Maximum exposure to loss in significant unconsolidated VIEs, debt investments This element represents the maximum funded exposure to loss in a significant unconsolidated variable interest entity, related to equity investments. Variable Interest Entity Equity Investments Funded Maximum Exposure to Loss Maximum exposure to loss in significant unconsolidated VIEs, equity investments This element represents the maximum unfunded exposure to loss in a significant unconsolidated variable interest entity, related to funding commitments. Variable Interest Entity Funding Commitments Unfunded Maximum Exposure to Loss Maximum exposure to loss in significant unconsolidated VIEs, funding commitments Notional amount This element represents the maximum unfunded exposure to loss in a significant unconsolidated variable interest entity, related to guarantees and derivatives. Variable Interest Entity Guarantees and Derivatives Unfunded Maximum Exposure to Loss Maximum exposure to loss in significant unconsolidated VIEs, guarantees and derivatives Variable Interest Entity by Type [Axis] Variable interests in a Variable interest entity (VIE) categorized by various types of securities both consolidated and unconsolidated held by an enterprise. Unfunded Exposure Unfunded Exposure [Abstract] Funded Exposure Funded Exposure [Abstract] Maximum exposure to loss in significant unconsolidated VIEs Variable Interest Maximum Exposure to Loss [Abstract] Non Marketable Equity Securities Fair Value Non-marketable equity securities carried at fair value This element represents the fair value of non-marketable equity securities. Available For Sale Securities Debt Securities [Member] This element represents the investments in available-for-sale debt securities. Total debt securities AFS Available For Sale Securities Equity Securities [Member] This element represents investments in marketable equity securities which are categorized as available-for-sale securities. Marketable equity securities AFS Held To Maturity Debt Securities Unrealized Credit Losses, Balance Net unrealized loss recognized in AOCI This item represents the adjustments to the amortized cost of investments held-to-maturity debt securities related to credit losses that are considered other-than-temporary impairments. Mortgage Backed Securities, Default Rate Projection Current Loans This element represents the projected percentage default rate of loans for which the performance is current, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. Default rate projection, loan performance current (as a percent) Default rates projection Default Rate Projection [Abstract] Prepayment Rate, Minimum This element represents the minimum projected prepayment rate CRR which is the annualized expected rate of voluntary prepayment of principal for mortgage-backed securities over a certain period of time. Prepayment rate, Minimum Unemployment Rate This element represents the projected unemployment rate, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. Increase (decrease) in unemployment rate (as a percent) Key assumptions for mortgage-backed securities Key Base Assumptions for Mortgage Backed Securities [Abstract] Prime bonds low end (as a percent) Loss Severity Rates for Prime Bonds Percentage Low End This element represents the low end of the range of the projected loss severity rate on prime bonds. Loss Severity Rates for Prime Bonds Percentage High End This element represents the high end of the range of the projected loss severity rate on prime bonds. Prime bonds high end (as a percent) Loss Severity Rates For Alt A Bonds Percentage Low End This element represents the low end of the range of the projected loss severity rate on Alt A bonds. Alt-A bonds low end (as a percent) Loss Severity Rates For Alt A Bonds Percentage High End This element represents the high end of the range of the projected loss severity rate on Alt A bonds. Alt-A bonds high end (as a percent) Loss Severity Rates for Subprime Bonds Percentage Low End This element represents the low end of the range of the projected loss severity rate on Subprime bonds. Subprime bonds low end (as a percent) Loss Severity Rates for Subprime Bonds Percentage High End This element represents the high end of the range of the projected loss severity rate on Subprime bonds. Subprime bonds high end (as a percent) Loss Severity Rates Loss Severity Rates [Abstract] Assumptions for U.S. Housing Price Valuations Changes in U.S. Housing Prices [Abstract] Housing Prices Increase Percentage Change Assumptions Next Calendar Year This element represents the projected percentage increase change in housing prices for the calendar year following the current fiscal year, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. U.S. housing price percentage increase (decrease) change for 2012 Housing Prices Increase Percentage Change Assumptions Future Calendar Year Two This element represents the projected percentage increase change in housing prices for the calendar year that is two years after the current fiscal year, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. U.S. housing price percentage increase (decrease) change for 2013 Housing Prices Change Assumptions, Future Calendar Year Three This element represents the projected change in housing prices for the calendar year that is three years after the current fiscal year, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. U.S. housing price change for 2014 (as a percent) Housing Prices Change Assumptions, Future Calendar Year Four This element represents the projected change in housing prices for the calendar year that is four years after the current fiscal year, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. U.S. housing price change for 2014 (as a percent) Schedule of Other than Temporary Impairment Losses Recognized in Earnings Investments [Table] Summarization of other-than-temporary impairment losses on investments that are recognized in earnings during the period. Schedule Of Available For Sale And Held To Maturity Securities Major Types Of Debt And Equity Securities [Axis] This element represents the summarization of securities considered for calculation of other than temporary impairments. Schedule Of Available For Sale And Held To Maturity Securities Major Types Of Debt And Equity Securities [Domain] This element represents the categories of securities considered for calculation of other than temporary impairments. Schedule of Available-for-sale and Held-to-maturity Securities Schedule Of Available For Sale And Held To Maturity Securities [Line Items] OTTI on Investments disclosures Impairment Losses Related to Securities [Abstract] Other than Temporary Impairment Losses, Investments with Intent Not to Sell For investments that the entity does not intend to sell nor will likely be required to sell, the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, prior to considering whether or not such amount is recognized in earnings or other comprehensive income. Total OTTI losses recognized during the year Other than Temporary Impairment Losses, Investments Not Being Sold, Portion Recognized in Earnings, Net Net impairment losses recognized in earnings for securities that the Company does not intend to sell nor will likely be required to sell For investments that the entity does not intend to sell nor will likely be required to sell, the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, the amount recognized in earnings for securities (after net of the amount recognized in other comprehensive income). Other than Temporary Impairment Losses, Investments with Intent to Sell OTTI losses recognized in earnings for securities that the Company intends to sell or more- likely-than-not will be required to sell before recovery For investments that the entity does intend to sell or will more-likely-than-not be required to sell before recovery, the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, the amount recognized in earnings for securities. Other-than-temporary-impairment charges Other than Temporary Credit Impairment Reductions Due to Sale of Credit Impaired Securities Sold or Matured This element represents amount of reduction in credit impairment recognized in earnings for available-for-sale and held to maturity investments, which were sold or matured during the period. Reductions due to credit impaired securities sold, transferred or matured Schedule of Delinquent Loans Schedule of Delinquent Loans [Line Items] Funding Commitments for Significant Unconsolidated VIEs Variable Interest Entity Funding Commitments [Line Items] Securitized credit card receivables Securitized Credit Card Receivables [Line Items] Ownership interests in principal amount of trust credit card receivables Ownership Interests in Principal Amount of Trust Credit Card Receivables [Abstract] Portion of Principal Amount Outstanding of Securitized Assets and Any Other Financial Assets Managed Together Sold to Investors via Trust Credit Card Receivables Sold to investors via trust-issued securities This element represents the ownership interests in principal amount of trust credit card receivables sold to investors via trust-issued securities. Portion of Securitized Assets and Any Other Financial Assets Managed Together Retained by Trust Issued Securities Retained by Citigroup as trust-issued securities This element represents the ownership interests in principal amount of trust credit card receivables retained by the reporting entity as trust-issued securities. Other Retained Interests in Securitized Assets on Credit Card Securitizations Other retained interests in securitized assets This element represents other amounts recorded on the balance sheet which are related to other retained interests in securitized assets of credit card receivables trusts. Residual Interest in Securitized Assets on Credit Card Securitizations Residual interest in securitized assets This element represents other amounts recorded on the balance sheet related to interests retained in the credit card receivables trusts for residual interest in securitized assets. Amounts Payable to Trusts on Credit Card Securitizations Amounts payable to trusts This element represents other amounts recorded on the balance sheet related to interests retained in the credit card receivables trusts for the purpose of amounts payable to trusts. Derivative Instruments Considered Guarantees [Member] Represents only those derivative instruments that require the entity to make payments to the counterparty based on changes in an underlying that is related to an asset, a liability, or an equity security held by the guaranteed party. More specifically, derivative instruments considered to be guarantees include certain over-the-counter written put options where the counterparty is not a bank, hedge fund or broker-dealer (such counterparties are considered to be dealers in these markets, and may therefore not hold the underlying instruments). Derivative instruments considered to be guarantees Net Unbilled Interest Receivables on Credit Card Receivables Net unbilled interest This element represents the amount of net unbilled interest included in the balance of residual interest in securitized assets of credit card receivables trusts. Portion Of Securitized Assets And Any Other Financial Assets Managed Together Retained By Reporting Entity Via Non Certificated Interests Retained by Citigroup via non-certificated interests This element represents the ownership interests in principal amount of trust credit card receivables retained by the reporting entity via non-certificated interests. Credit card merchant processing guarantees represent the Company's indirect obligations in connection with the processing of private label and bank card transactions on behalf of merchants. Credit card merchant processing Credit Card Merchant Processing [Member] Custody Indemnifications and Other [Member] Custody indemnifications are issued to guarantee that custody clients will be made whole in the event of a third-party sub-custodian or depository institution failing to safeguard clients' assets. Custody indemnifications and other External Credit Rating Not Rated [Member] Represents underlying referenced credits or entities, with respect to guarantees, for which ratings are not available. Not rated Maximum potential amount of future payments Guarantee Obligations Maximum Exposure [Abstract] Expire Within One Year Guarantee Obligations Maximum Exposure Expire within One Year Represents the maximum potential payments with respect to the entity's guarantees that expire within one year. Guarantee Obligations Maximum Exposure Expire after One Year Expire After One Year Represents the maximum potential payments with respect to the entity's guarantees that expire after one year. Loans Sold with Recourse [Member] Represents the entity's obligations to reimburse the buyers for loan losses under certain circumstances. Recourse refers to the clause in a sales agreement under which a lender will fully reimburse the buyer/investor for any losses resulting from the purchased loans. This may be accomplished by the seller's taking back any loans that become delinquent. Loans sold with recourse Securities Lending Indemnifications [Member] Represents the indemnifications issued by the bank with regard to securities lending to guarantee that a securities lending customer will be made whole in the event that the security borrower does not return the security subject to the lending agreement and the collateral held is insufficient to cover the market value of the security. Securities lending indemnifications Reserve for Visa Litigation Matters Accrual related to Visa USA's and MasterCard's litigation matters Represents the carrying value of the entity's accrual related to Visa's litigation matters. Letters of Credit Received as Collateral Letters of credit in favor of the Company held as collateral Represents the letters of credit in favor of the entity held as collateral to reimburse losses realized under the guarantees. Fair Value of Trusts Funded by Insurer Fair value of securities in trusts funded by reinsurer relating to indemnification Represents the fair value of securities relating to the funding of the trusts by the reinsurer to cover the insurance company's statutory liabilities for long-term care (LTC) Policies. Available-for-sale Securities, Debt Maturities [Abstract] Available-for-sale Securities, Debt Maturities Interest and Dividend Income, Securities, by Taxable Status [Abstract] Interest and dividends on all investments Debt Securities Held-to-maturity Schedule of Held-To-maturity Securities [Abstract] Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract] Held-to-maturity Securities, Continuous Unrealized Loss Position Auction Rate Securities Outstanding in Capacity of Primary Dealer Amount of auction rate securities in which Citigroup acted in the capacity of primary dealer This element represents the value of auction rate securities for which the entity acted in the capacity of primary dealer. Weighted Average F I C O Scores Of Collateral Low End Weighted average FICO score of the underlying collateral for Alt-A mortgage securities recorded at fair value, low end of range The low end weighted average FICO scores of underlying collateral of Alt-A non-agency residential mortgage-backed securities. Weighted Average F I C O Scores Of Collateral High End Weighted average FICO score of the underlying collateral for Alt-A mortgage securities recorded at fair value, high end of range The high end weighted average FICO scores of underlying collateral of Alt-A non-agency residential mortgage-backed securities. Percentage of RMBS with Full Documentation Loans if FICO Scores Greater than 720 Residential mortgage-backed securities (RMBS) where collateral is composed of full documentation loans, above the high end of range (as a percent) The percentage of collateral of residential mortgage-backed securities with full documentation loans, where FICO scores are greater than 720. This element represents the different types of fees and commissions earned during the period. Income from Fees and Commission Sources Name [Domain] Gross Inventory [Member] Represents the total value of the asset or liability prior to the netting of: a) the amounts due under securities purchased under agreements to resell and the amounts owed under securities sold under agreements to repurchase, and b) derivative exposures covered by a qualifying master netting agreement, cash collateral, and the market value adjustment. Gross inventory Netting [Member] Represents the amount of netting to an asset or liability due to: a) the amounts due under securities purchased under agreements to resell and the amounts owed under securities sold under agreements to repurchase, and b) derivative exposures covered by a qualifying master netting agreement, cash collateral, and the market value adjustment. Netting Non Marketable Equity Securities [Member] Non-marketable equity securities that are carried at fair value which are categorized neither as trading, held-to-maturity nor available-for-sale securities. Non-marketable equity securities Percentage of Assets to Gross Assets Total as a percentage of gross assets This element represents the percentage of total assets to gross assets. Percentage of Liabilities to Gross Liabilities Total as a percentage of gross liabilities This element represents the percentage of total liabilities to gross liabilities. Income from Fees and Commission [Table] Encapsulates the table having details of income from fees and commissions. Income from Fees and Commission Sources [Axis] This element represents the different types of fees and commissions earned during the period. Credit card and bank card fees are primarily composed of interchange revenue and certain card fees, including annual fees, reduced by reward program costs. Interchange revenue and fees are recognized when earned, except for annual card fees which are deferred and amortized on a straight-line basis over a 12-month period. Reward costs are recognized when points are earned by the customers. Credit Card and Bank Card [Member] Credit cards and bank cards This element represents fees and commissions earned from advisory and equity and debt underwriting services. Investment Banking [Member] Investment banking Trading Related [Member] Trading-related fees primarily include commissions and fees from the following: executing transactions for client on exchanges and over-the-counter markets; sale of mutual funds, insurance and other annuity products; and assisting clients in clearing transactions, providing brokerage services and other such activities. Trading-related fees are recognized when earned in Commissions and fees. Gain or losses, if any, on these transactions are included in Principal transactions. Trading-related Other Consumer [Member] This element represents fees and commissions earned from consumer services which consists primarily of fees for investment fund administration and management, third-party collections, commercial demand deposit accounts and certain credit card services. Other Consumer Checking Related [Member] This element represents fees and commissions earned from checking related activity. Checking-related This element represents a number of concepts which are required or determined to be provided for purposes of reconciling beginning and ending balances of fair value measurements of assets and liabilities using significant unobservable inputs (Level 3). Such reconciliation, separately presenting changes during the period, at a minimum, may include: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (net); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs). Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation by Asset Type [Axis] Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation Asset Types [Domain] This element provides general categories of investment (assets and liabilities) for which the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (net); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs). Assets [Member] This element represents the total assets. Assets: Total assets Other Financial Assets [Member] This element represents the financial assets not otherwise disclosed separately. Other financial assets measured on a recurring basis Nontrading derivatives and other financial assets measured on a recurring basis Liabilities [Member] This element represents the total liabilities. Liabilities- Other Financial Liabilities [Member] This element represents the financial liabilities not otherwise disclosed separately. Other financial liabilities measured on a recurring basis Primerica [Member] This element represents fees and commissions earned from Primerica. Primerica Loan Servicing [Member] This element represents fees and commissions earned from servicing of loan assets, including fair value adjustment of mortgage servicing assets. Loan servicing Corporate Finance [Member] This element represents fees and commissions earned on corporate finance activity which consists primarily of fees earned from structuring and underwriting loan syndications. Corporate finance COMMISSIONS AND FEES Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Table] Summarization of information required and determined to be provided for purposes of reconciling beginning and ending balances of fair value measurements of assets and liabilities using significant unobservable inputs (Level 3). Such reconciliation, separately presenting changes during the period, at a minimum, may include: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (net); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs). Nikko Cordial [Member] This element represents the discontinued operations of Nikko Cordial. Nikko Cordial Securities Asset Management Business [Member] This element represents the discontinued operations of asset management business. Asset Management business Disposal Group Including Discontinued Operation Transaction Cash Value This element represents the total cash value of the discontinued operation disposal transaction. Total cash value of the discontinued operation disposal transaction Contingent Consideration Received of Previously Discontinued Operation Pretax This element represents the contingent consideration payment received, which is related to the sale of a business that was classified as a discontinued operation in the previous reporting period, as shown before tax. Contingent consideration payment received, pretax Contingent Consideration Received of Previously Discontinued Operation, after Tax This element represents the contingent consideration payment received, which is related to the sale of a business that was classified as a discontinued operation in the previous reporting period, as shown net of tax. Contingent consideration payment received, after-tax Disposal Group, Not Discontinued Operation, Income Statement Disclosures [Abstract] Results of Discontinued Operations Disposal Group Including Discontinued Operation Transaction Value Allocation to Equity Securities This element represents the portion of the total value of the discontinued operations' disposal transaction that resulted from the purchase price of the equity securities held by the business being sold. Purchase price of certain Japanese-listed equity securities held by the business being sold Citigroup Capital VIII Citigroup Capital V I I I [Member] This element represents Citigroup Capital VIII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital I X [Member] This element represents Citigroup Capital IX, a trust security with distributions guaranteed by Citigroup. Citigroup Capital IX Citigroup Capital X [Member] This element represents Citigroup Capital X, a trust security with distributions guaranteed by Citigroup. Citigroup Capital X This element represents the carrying values of trust preferred securities. Carrying value of Principal-Protected Trust Securities Trust Preferred Securities, Carrying Value Line of Credit Facility Termination Prior Period Notice This element represents the notice period required to terminate the line of credit facility. Notice period banks are required to give CGMHI prior to terminating financing facilities (in years) Schedule of Trust Preferred Securities [Table] This element represents the schedule of outstanding trust preferred securities, which may include issuance date, number of securities issued, liquidation value, coupon rate, common shares issued to parent and other necessary information. Schedule of Trust Preferred Securities by Type of Securities [Axis] This element represents the schedule of outstanding trust preferred securities, by type of securities. Disposal Group Including Discontinued Operation Transaction Value Allocation to Excess Cash This element represents the portion of the total value of the discontinued operations' disposal transaction that resulted from excess cash derived through the repayment of outstanding indebtedness to the reporting entity. Excess cash derived through the repayment of outstanding indebtedness to Citi Schedule of Trust Preferred Securities [Table Text Block] Schedule of Statutory Business Trusts This element represents the complete disclosure related to trust preferred securities, including issuance date, number of securities issued, liquidation value, coupon rate, and other necessary information. Trust Preferred Securities by Type of Securities [Domain] This element represents the list of outstanding trust preferred securities, by type of securities. Citigroup Capital I I I [Member] This element represents Citigroup Capital III, a trust security with distributions guaranteed by Citigroup. Citigroup Capital III Citigroup Capital V I I [Member] This element represents Citigroup Capital VII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital VII Citigroup Capital X I [Member] This element represents Citigroup Capital XI, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XI Citigroup Capital X I I [Member] This element represents Citigroup Capital XII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XII Citigroup Capital X I V [Member] This element represents Citigroup Capital XIV, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XIV Citigroup Capital X V [Member] This element represents Citigroup Capital XV, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XV Citigroup Capital X V I [Member] This element represents Citigroup Capital XVI, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XVI Citigroup Capital X V I I [Member] This element represents Citigroup Capital XVII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XVII Citigroup Capital X V I I I [Member] This element represents Citigroup Capital XVIII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XVIII Citigroup Capital X I X [Member] This element represents Citigroup Capital XIX, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XIX Citigroup Capital X X [Member] This element represents Citigroup Capital XX, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XX Citigroup Capital X X I [Member] This element represents Citigroup Capital XXI, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XXI Citigroup Capital X X X [Member] This element represents Citigroup Capital XXX, a trust security with distributions guaranteed by Citigroup. Citigroup Capital trust XXX Citigroup Capital X X X I [Member] This element represents Citigroup Capital XXXI, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XXXI Citigroup Capital X X X I I [Member] This element represents Citigroup Capital XXXII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital trust XXXII Citigroup Capital X X X I I I [Member] This element represents Citigroup Capital XXXIII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XXXIII Adam Capital Trust I I I [Member] This element represents Adam Capital Trust III, a trust security with distributions guaranteed by Citigroup. Adam Capital Trust III Adam Statutory Trust I I I [Member] This element represents Adam Statutory Trust III, a trust security with distributions guaranteed by Citigroup. Adam Statutory Trust III Adam Statutory Trust I V [Member] This element represents Adam Statutory Trust IV, a trust security with distributions guaranteed by Citigroup. Adam Statutory Trust IV Adam Statutory Trust V [Member] This element represents Adam Statutory Trust V, a trust security with distributions guaranteed by Citigroup. Adam Statutory Trust V Trust Securities Trust Preferred Securities [Line Items] Trust Preferred Securities Issued This element represents the number of trust preferred securities issued as of the balance sheet date. Securities issued (in shares) Trust Preferred Securities Liquidation Value This element represents the notional value received by investors from the trusts at the time of issuance. Liquidation value Trust Preferred Securities Coupon Rate This element represents the coupon rate of the trust preferred securities. Coupon rate (as a percent) This element represents the common shares issued by subsidiary trust to parent. Common shares issued to parent Subsidiary Trust Common Shares Issued to Parent Investments in Alternative Investment Funds [Table Text Block] This item represents the disclosure of investments in alternative investment funds. Investments in Alternative Investment Funds Other than Temporary Impairment Losses, Investments Recognized in Earnings, Net Total impairment losses recognized in earnings For investments, the amount by which the fair value of an investment is less than the amortized cost basis or carrying amount at the balance sheet date and the decline in fair value is deemed to be other than temporary, the amount recognized in earnings for securities, net of amount recognized in other comprehensive income. Citibank Credit Card Master Trust [Member] This element represents the Citibank Credit Card Master Trust, which is part of Citicorp. Citibank Credit Card Master Trust (Master Trust) Citibank O M N I Master Trust [Member] This element represents the Citibank OMNI Master Trust, which is substantially part of Citicorp. Citibank OMNI Master Trust (Omni Trust) Citibank Broadway Credit Card Trust [Member] This element represents the Broadway Credit Card Trust, which is part of Citi Holdings. Citibank Broadway Credit Card Trust (Broadway Trust) This element represents the Company's investment in certificates issued by the trusts of the newly consolidated VIE's that were classified as Level 3 for fair value measurement purposes. Investment in certificates issued by trusts of the newly consolidated VIE's that were classified as Level 3 Investment in Consolidated Variable Interest Entities Certificates Classified as Level Three This element represents the losses on hedged senior debt securities that were sold. Losses on hedged senior debt securities Losses on Hedged Senior Debt Securities Key Assumptions for Mortgage Backed Securities [Table Text Block] This item represents the summary of key assumptions for mortgage-backed securities. Key assumptions for mortgage-backed securities Citibank Credit Card Master Trust And O M N I Master Trust [Member] This element represents the aggregate of the Citibank Credit Card Master Trust and the Citibank OMNI Master Trust. Citibank Credit Card Master Trust (Master Trust) and OMNI Master Trust (Omni Trust) Funding, Liquidity Facilities and Subordinated Interests Funding Liquidity Facilities and Subordinated Interests [Line Items] Weighted average maturity of term notes (in years) Weighted Average Maturity of Term Notes This element represents the weighted average maturity of the term notes. Commercial Paper under Commercial Paper Funding Facility Liabilities funded through Federal Reserve's Commercial Paper Funding Facility (CPFF) The amount of liabilities funded through the Federal Reserve's Commercial Paper Funding Facility. Term Notes Issued to Third Parties Term notes issued to third parties The par value of liabilities of the credit card receivables securitization trust related to term notes issued to third parties. Term Notes Retained by Affiliates Term notes retained by Citigroup affiliates The par value of liabilities of the credit card receivables securitization trust related to term notes retained by affiliates of the entity. Excess of Risk Weighted Assets over Tier One Capital The decrease in the Tier 1 Capital Ratio, expressed in terms of basis points, due to the inclusion of sold assets for the credit card securitization trusts in the risk-weighted assets for purposes of calculating risk-based capital ratios. Decrease in Tier 1 Capital ratio (in basis points) Amount of Increase in Risk Weighted Assets Increase in risk-weighted assets The increase in risk-weighted assets due to the inclusion of sold assets for the credit card securitization trusts in the risk-weighted assets for purposes of calculating risk-based capital ratios. Classification of Securitizations Classification of Securitizations [Line Items] This element represents hedge funds and equities. Hedge Funds and Equities [Member] Hedge funds and equities Schedule of funding commitments of unconsolidated Variable Interest Entities This element represents the schedule of funding commitments of unconsolidated Variable Interest Entities. Schedule of Funding Commitments of Unconsolidated Variable Interest Entities [Table Text Block] Schedule of Significant Interests in Unconsolidated Variable Interest Entities [Table Text Block] Schedule of significant interests in unconsolidated VIEs - balance sheet classification This element represents the schedule of carrying amounts and classifications of significant interests in unconsolidated VIEs. Schedule of Securitized Credit Card Receivables [Table Text Block] Schedule of securitized credit card receivables This element represents the schedule of securitized credit card receivables. Schedule of Managed Loans of Subsidiary One [Table Text Block] Schedule of reconciliation between managed loans and on-balance-sheet credit card portfolios and related delinquencies and credit losses of Citicorp This element represents the schedule of reconciliation between managed loans and on-balance-sheet credit card portfolios and the related delinquencies and credit losses, net of recoveries, of the first segment. Schedule of Managed Loans of Subsidiary Two [Table Text Block] Schedule of reconciliation between managed loans and on-balance-sheet credit card portfolios and related delinquencies and credit losses of Citi Holdings This element represents the schedule of reconciliation between managed loans and on-balance-sheet credit card portfolios and the related delinquencies and credit losses, net of recoveries, of the second segment. This element represents corporate loans. Corporate Loans [Member] Corporate loans This element represents airplanes, ships and other assets. Airplanes Ships and Other Assets [Member] Airplanes, ships and other assets Economic interest in the long-term care business (as a percent) Ownership interest (as a percent) Percentage of Ownership Interest in Subsidiary This element represents the percentage of ownership interest in a subsidiary company directly or indirectly held by the reporting entity. Mortgage Service Rights [Member] This element represents mortgage servicing rights (MSR). Mortgage servicing rights: Type of Assets [Axis] This element represents the classification of assets. This element represents the classification of assets. Type of Assets [Domain] Schedule of selected cash flow information related to asset-based financing This element represents the schedule of selected cash flow information related to asset-based financing. Schedule of Selected Cash Flow Information Related to Asset Based Financing [Table Text Block] Classification of Other Securitization Details Classification of Other Securitization Details [Line Items] Weighted Average Life of Commercial Paper Weighted average life of commercial paper (in days) This element represents the weighted average life, in days, of short-term commercial paper. Schedule of Trust One Liabilities [Table Text Block] Schedule of Master Trust liabilities (at par value) This element represents the schedule of liabilities of credit card receivables securitization trusts, for the first trust. Schedule of Trust Two Liabilities [Table Text Block] Schedule of Omni Trust liabilities (at par value) This element represents the schedule of liabilities of credit card receivables securitization trusts, for the second trust. Schedule of Fees Received on Mortgage Servicing Rights [Table Text Block] Schedule of fees received on servicing previously securitized mortgages This element represents the schedule of fees received on servicing previously securitized mortgages. Schedule of Trust Three Liabilities [Table Text Block] Schedule of Broadway Trust liabilities (at par value) This element represents the schedule of liabilities of credit card receivables securitization trusts, for the third trust. Weighted Average Life of Commercial Paper Issued by Conduits Weighted average life of commercial paper issued by conduits (in days) This element represents the weighted average life, in days, of commercial paper issued by the conduits. Notional Amount of Subordinated Notes and Equity Notional amount of subordinated loss notes and equity This element represents the notional amount of subordinated loss notes and equity. Tenor of Subordinated Notes and Equity Low End of Range Tenor of subordinated notes and equity, low end of range (in months) This element represents the low end of the range of tenor of subordinated notes and equity. Tenor of Subordinated Notes and Equity High End of Range Tenor of subordinated notes and equity, high end of range (in years) This element represents the high end of the range of tenor of subordinated notes and equity. Letters of Credit as Percentage of Conduit Assets Letters of credit as percentage of conduit assets This element represents the percentage of letters of credit to conduit assets. Letters of credit provided to conduits Letters of Credit Provided to Conduits This element represents the letters of credit provided to conduits. Maximum Exposure of Loss under Program Wide Liquidity Arrangements Notional exposure under program-wide liquidity agreement This element represents the maximum exposure of loss under program wide liquidity arrangements. Assets Unconsolidated Government Guaranteed Loan Conduit Assets held by unconsolidated government guaranteed loan conduit This element represents the amount of assets held in the unconsolidated government-guaranteed loan conduit. Notional Amount of Commercial Paper under Third Party Conduits Notional amount of commercial paper under third party conduits This element represents the notional amount of commercial paper issued under third party conduits. Commercial Paper Issuance Description of Variable Rate Basis Commercial paper issuance, description of variable rate basis The reference rate for the specified maximum variable rate of interest related to the issuance of commercial paper under the terms of the liquidity puts. Commercial Paper Issuance Limit On L I B O R Variable Rate Commercial paper issuance, limit on LIBOR variable rate (in basis points) Represents the basis points added to the reference rate to compute the specified maximum variable rate of interest related to the issuance of commercial paper under the terms of the liquidity puts. Number of Consolidated Collateralized Debt Obligation Vehicles Number of collateralized debt obligation vehicles consolidated This element represents the number of collateralized debt obligation vehicles consolidated during the period. Maximum Percentage of Junior Residual Securities to Total Trust Funding Percentage of maximum residuals to total trust funding This element represents the percentage by which residuals are frequently less than the trust's total funding. Municipal Bonds Owned by Trust with Credit Guarantee Municipal bonds owned by trusts, that have credit guarantee provided by the Company This element represents the amount of municipal bonds owned by trusts that have a credit guarantee provided by the entity. Percentage of residuals to trust capital structure, for determining reimbursement agreement with residual holder Percentage Of Residuals To Trusts Capital Structure In Customer T O B The percentage whereby if the customer TOB's residual is less than this specified percentage of the trust's capital structure, the entity has a reimbursement agreement with the residual holder. Liquidity Agreements For Customer T O B Trust Liquidity agreements, customer TOB trust This element represents the amount of liquidity agreements for customer TOB trusts. Residuals Held By Hedge Funds In Proprietary T O B Trust Residuals held by hedge funds, consolidated and managed, proprietary TOB trusts The amount of assets in proprietary TOB trusts where the residuals are held by hedge funds that are consolidated and managed by the entity. This element represents the fair value of liability measured with unobservable inputs reconciliation recurring basis. Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Liability Balance at beginning of period, liability Balance at end of period, liability Principal amount of credit card receivables in trusts This element represents the principal amount of credit card receivables held in trusts. Securitized Credit Card Receivables Principal Amount Outstanding Total ownership interests in principal amount of trust credit card receivables Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Table Text Block] This element represents, for the fair value measurement of assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (net); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs). Changes in level 3 fair value category Incremental Effect of New Accounting Pronouncement on Assets from Deconsolidation Incremental effect of adopting SFAS 166/167 on assets from deconsolidation The incremental increase (decrease) in assets from deconsolidation resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. This element represents the held to maturity investments other than mortgage-backed securities and state and municipal securities. Asset Backed And Other Debt Securities [Member] All Other Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract] Held-to-maturity Securities, Debt Maturities, Fair Value; Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] Held-to-maturity Securities, Debt Maturities, Net Carrying Amount; Held-to-maturity Securities, Debt Maturities [Abstract] Held-to-maturity Securities, Debt Maturities Incremental effect of adopting SFAS 166/167 on risk-weighted assets from deconsolidation Incremental Effect of New Accounting Pronouncement or Change in Accounting Principle on Risk Weighted Assets from Deconsolidation The incremental increase (decrease) in risk-weighted assets from deconsolidation resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Variable Interest Entity by Type [Domain] Variable interests in a Variable interest entity (VIE) categorized by various types of securities both consolidated and unconsolidated held by an enterprise. Variable Interest Carrying Amount Unconsolidated Assets The assets of significant VIEs, as of the date of adoption of new accounting standards, with which the entity is involved that were previously unconsolidated and are required to be consolidated under new accounting standards. Previously unconsolidated assets of VIE Schedule of Interest Revenues and Expenses [Table Text Block] Disclosure of the components of interest revenue and interest expense for the reporting period. Interest revenue and expense Decrease in Deferred Tax Assets Elimination of Deduction for Medicare Prescription Drug Benefit Subsidy Reduction in deferred tax assets, elimination in deductibility of Medicare Part D subsidy The decrease in deferred tax assets resulting from new legislation which eliminates the tax deductibility for benefits paid that are related to the retiree Medicare Part D subsidy. Nonqualified U S Pension Plans Defined Benefit [Member] Defined benefit pension plan of a U.S. reporting entity that is considered a nonqualified plan for U.S. tax purposes. Nonqualified U.S. pension plans Interest and dividend income on all securities excluding trading securities. Interest and Dividend Income Securities Excluding Trading Securities Investments, including dividends Total interest and dividends Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract] Fair value, assets and liabilities measured on recurring basis Voting Rights Percentage Trigger Consolidation Minimum voting rights percentage for consolidation The minimum voting rights percentage owned by the entity that triggers consolidation. Maximum Ownership Percentage Income Recognition upon Receipt of Dividends Ownership percentage, if less than this amount then income from investments is recognized when dividends are received The maximum percentage of ownership for the entity to reflect recognition of income as dividends is received. Repurchase and Resale Agreements, and Securities Lending and Borrowing Agreements Accounted for as Sales Repurchase and Resale Agreements and Securities Lending and Borrowing Agreements Accounted for as Sales [Abstract] Repurchase agreements and securities lending agreements accounted for as sales Repurchase Agreements and Securities Lending Agreements Accounted for as Sales The amount of repurchase agreements and securities lending agreements that were accounted for as sales and a reduction to trading account assets as of the balance sheet date. The incremental increase (decrease) in assets from consolidation resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Incremental effect of adopting SFAS 166/167 on assets from consolidation Incremental Effect of New Accounting Pronouncement on Assets from Consolidation Assets Impacted by Change in Accounting [Axis] The types of asset accounts impacted by the adoption of a new accounting pronouncement or a change in accounting principle. Type of Asset Impacted by Change in Accounting [Domain] The asset accounts impacted by the adoption of a new accounting pronouncement or a change in accounting principle. This element represents fees and commissions earned by the entity, not otherwise defined in the taxonomy. Other Commission and Fee Revenue [Member] Other Transfer of Qualifying Special Purpose Entity Accounted as Sales Assets of QSPEs that Citigroup transferred and received sales treatment The portion of assets of former qualified special purpose entities (QSPEs) to which the entity, acting as principal, had transferred assets and received sales treatment prior to the adoption of a new accounting pronouncement. Repurchase Agreements and Securities Lending Agreements Accounted for as Sales in Error Repurchase agreements and securities lending agreements accounted for as sales in error The amount of repurchase agreements and securities lending agreements that were accounted for as sales in error as of the balance sheet date. Quantifying Misstatement for Repurchase Agreements in Financial Statements Assets Percent Repurchase and securities lending recorded as sales in error as a percentage of total assets Impact of error in accounting for repurchase agreement and securities lending agreements accounted for as sales on total assets, as a percentage of total assets. Quantifying Misstatement for Repurchase Agreements in Financial Statements Liabilities Percent Repurchase and securities lending recorded as sales in error as a percentage of total liabilities Impact of error in accounting for repurchase agreement and securities lending agreements accounted for as sales on total liabilities, as a percentage of total liabilities. Quantifying Misstatement for Repurchase Agreements in Financial Statements Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase Percent Repurchase and securities lending recorded as sales in error as a percentage of Federal funds purchased and securities loaned or sold under agreements to repurchase Impact of error in accounting for repurchase agreement and securities lending agreements accounted for as sales on total Federal funds purchased and securities loaned or sold under agreements to repurchase, as a percentage of this financial statement line item. Other than Temporary Impairment Losses Investments [Table Text Block] This item represents the disclosure of other-than-temporary impairment losses on investments. Total other-than-temporary impairments recognized Commissions and fees revenues Schedule of commission and fee revenues earned by the entity. Schedule of Commission and Fee Revenue [Table Text Block] Disposal Group Including Discontinued Operations Transaction Value of Business Disposition Value of the business disposal transaction The value of the disposal transaction of a business being sold, or to be sold, as part of a disposal group or discontinued operation. Number of employees included in the sale of discontinued operations This element represents the number of employees included in the discontinued operation. Disposal Group Including Discontinued Operations Number of Employees Amortized cost This item represents the cost of investments in debt securities which are categorized as held-to-maturity, net of adjustments for accretion and amortization. This item does not include any adjustments related to credit losses that are considered other-than-temporary impairments. Held To Maturity Debt Securities Amortized Cost Basis Schedule of Disposal Groups Including Discontinued Operations Nikko Central [Table Text Block] The summarized financial disclosures relating to the sale of Nikko Cordial, which is classified as a discontinued operation. Summarized financial information for Nikko Cordial QSPE assets Qualified Special Purpose Entity Carrying Amount Assets The carrying amount of the Qualified Special Purpose Entity assets included in the reporting entity's statement of financial position. Special Purpose Entity Total Involvement With S P E Assets The amount of total involvement with Special Purpose Entity assets, including significant unconsolidated Variable Interest Entity assets and consolidated Variable Interest Entity and Special Purpose Entity assets. Total involvement with SPE assets Variable Interest Entity Nonconsolidated Involvement Assets The amount of involvement with significant unconsolidated Variable Interest Entity assets. Significant unconsolidated VIE assets Funding Commitment Types [Axis] This element represents the types of funding commitments. Funding Commitment Types [Domain] This element represents the types of funding commitments. Liquidity Facilities [Member] This element represents the notional amount of funding commitments for liquidity facilities of VIEs. Liquidity facilities Citigroup Loan Commitments [Member] This element represents the notional amount of funding commitments for loan commitments of VIEs. Loan commitments Citigroup Line of Credit Facility Amount Guaranteed by Parent Amount drawn down on long-term financing facilities guaranteed by Citigroup Amount borrowed under the credit facility as of the balance-sheet date that is guaranteed by parent entity. Junior Subordinated Debentures Owned by Trust Proceeds Received from Trust at Issuance This element represents the proceeds received from the trust at the date of issuance of the junior subordinated debentures to the trust. Junior subordinated debentures owned by the Trust, proceeds received from the Trust at the date of issuance Statement. Change in Each Component of Accumulated Other Comprehensive Income (Loss) [Line Items] Municipal Securities Tender Option Bond Trusts [Member] Municipal securities tender option bond trusts (TOBs) Represents the municipal securities tender option bond trusts. Amount funded under liquidity facilities This element represents the amount funded under the liquidity facilities. Liquidity Facilities Amount Funded Commercial paper purchased subject to liquidity puts The amount of commercial paper purchased subject to liquidity puts. Commercial Paper Purchased Subject to Liquidity Puts Other Citigroup Subsidiaries [Member] This element represents other Citigroup subsidiaries. Other Citigroup subsidiaries Schedule of Fair Value of Financial Instruments [Table Text Block] Estimated Fair Value of Financial Instruments Tabular disclosure of the carrying value and fair value of financial instruments. Municipal Investments [Member] This element represents municipal investments. Municipal investments The percentage of residual owned by the customer to the bond value, related to the remaining exposure with respect to customer TOB trusts. Percentage of minimum residual owned by customer to bond value, remaining exposure Percentage of Residual Owned by Customer to Bond Value The notional amount of reimbursement agreements in place, which offset liquidity agreements for customer TOB trusts. Notional amount of offsetting reimbursement agreements Notional Amount Reimbursement Agreements This element represents the notional amount of liquidity arrangements for other non-consolidated proprietary trusts. Notional amount to QSPE TOB trusts and other non-consolidated proprietary TOB trusts Notional Amount Liquidity Arrangements Other Aggregate unpaid principal balance in excess of fair value Fair Value Option Loans Held as Assets Aggregate Fair Value in Excess of Aggregate Unpaid Principal Balance For short-term borrowings which the fair value option has been elected, this item represents the amount by which the difference between the aggregate fair value and the aggregate unpaid principal balance. For trading assets which the fair value option has been elected, this item represents the carrying amount of those positions that are 90 days or more past due, in nonaccrual status, or both. Balance of non-accrual loans or loans more than 90 days past due Fair Value Option Loans Held as Assets Nonaccrual Status or 90 Days or More Past Due The payment of maturing notes related to securitizations. Payment of Maturing Notes Securitizations Pay down of maturing notes Issuance Of Notes Term Asset Backed Securities Loan Facility Program The amount of notes issued during the period that are eligible for the Term Asset-Backed Securities Loan Facility (TALF) program, where investors can borrow from the Federal Reserve using trust securities as collateral. Issuance of notes eligible for Term Asset-Backed Securities Loan Facility (TALF) program Commercial Paper Trust Liabilities The par value of liabilities of the credit card receivables securitization trust related to commercial paper. Commercial paper Securitization Trusts [Table] Schedule of information related to securitization trusts. Disclosure of information related to securitization trusts. Securitization Trusts [Axis] Securitization trusts. Securitization Trusts [Domain] Liquidity Commitment Trust Commercial Paper Program The amount of liquidity commitment related to the commercial paper program of the credit card receivable securitization trusts. Liquidity commitment to commercial paper programs of trusts Housing Price Change Assumptions Next Calendar Year U.S. housing price percentage increase assumption used, year one This element represents the assumption used for the projected percentage increase (decrease) in housing prices for the first calendar year following the current fiscal year. Housing Price Change Assumptions Future Calendar Year Two U.S. housing price percentage increase assumption used, year two This element represents the assumption used for the projected percentage increase (decrease) in housing prices for the second calendar year following the current fiscal year. Schedule Of Carrying Amounts And Classifications Of Consolidated V I E And S P E Assets [Table Text Block] Schedule of carrying amounts and classifications of consolidated assets that are collateral for consolidated VIE and SPE obligations This element represents the schedule of carrying amounts and classifications of consolidated assets that are collateral for consolidated VIE and SPE obligations. Schedule of Cash Flow Credit Card Securitizations Segment One [Table Text Block] Schedule of cash flow information, credit card securitizations of Citicorp This element represents the schedule of cash flow information related to the credit card securitizations of the first segment. Schedule of Cash Flow Credit Card Securitizations Segment Two [Table Text Block] Schedule of cash flow information, credit card securitizations of Citi Holdings This element represents the schedule of cash flow information related to the credit card securitizations of the second segment. Schedule of Cash Flow Mortgage Securitizations Segment One [Table Text Block] This element represents the schedule of cash flow information related to the mortgage securitizations of the first segment. Schedule of cash flow information, mortgage securitizations of Citicorp Schedule of Key Assumptions Measuring Fair Value of Retained Interests of Mortgage Receivables Segment One [Table Text Block] This element represents the schedule of key assumptions used in measuring fair value of retained interests at the date of sale or securitization of mortgage receivables of the first segment. Schedule of key assumptions used in measuring fair value of retained interest at the date of sale or securitization of mortgage receivables of Citicorp Schedule of Key Assumptions to Value Retained Interests and Sensitivity of Adverse Changes of 10 Percent and 20 Percent Mortgage Securitizations Segment One [Table Text Block] This element represents the schedule of key assumptions used to value retained interests and sensitivity of adverse changes of 10% and 20% for mortgage securitizations of the first segment. Schedule of key assumptions used to value retained interests and sensitivity of adverse changes of 10% and 20%, mortgage securitizations of Citicorp Schedule of asset-based financing of Citicorp Schedule Of Asset Based Financing Unconsolidated V I E Segment One [Table Text Block] This element represents the schedule of asset-based financing of the first segment. Schedule Of Asset Based Financing Unconsolidated V I E Segment Two [Table Text Block] Schedule of asset-based financing of Citi Holdings This element represents the schedule of asset-based financing of the second segment. Schedule of Sensitivity of Adverse Changes of 10 Percent and 20 Percent Discount Rate Asset Based Financing [Table Text Block] Schedule of sensitivity of adverse changes of 10% and 20% to discount rate, asset-based financing This element represents the schedule of sensitivity of adverse changes of 10% and 20% to the discount rate for asset-based financing. Liquidity Commitment Trust Third Party Conduit Liquidity commitment to third party conduit The amount of liquidity commitment related to the third party conduit of the credit card receivable securitization trusts. Number of Directors Right to Appoint after Increase in Ownership Stake Number of directors on board of LQIF that Citigroup has the right to appoint, after increase in ownership This element represents the number of directors on the board of the investee company that the reporting entity has the right to appoint, after the increase in stake in the investee company. Schedule of Cash Flow Mortgage Securitizations Segment Two [Table Text Block] This element represents the schedule of cash flow information related to the mortgage securitizations of the second segment. Schedule of cash flow information, mortgage securitizations of Citi Holdings Schedule of Key Assumptions to Value Retained Interests and Sensitivity of Adverse Changes of 10 Percent and 20 Percent Mortgage Securitizations Segment Two [Table Text Block] This element represents the schedule of key assumptions used to value retained interests and sensitivity of adverse changes of 10% and 20% for mortgage securitizations of the second segment. Schedule of key assumptions used to value retained interests and sensitivity of adverse changes of 10% and 20%, mortgage securitizations of Citi Holdings Schedule of Key Assumptions for Measuring Fair Value of Retained Interests of Collateralized Debt Obligations and Collateralized Loan Obligations Segment Two [Table Text Block] This element represents the schedule of key assumptions for measuring fair value of retained interests at the date of sale or securitization of CDOs and CLOs of the second segment. Schedule of key assumptions for measuring fair value of retained interests at the date of sale or securitization of CDOs and CLOs of Citi Holdings Number of Directors Investee Company Total number of directors on board of LQIF This element represents the total number of directors on the board of the investee company. Number of Directors of Related Company Right to Appoint after Increase in Ownership Stake Number of directors on board of Banco de Chile that Citigroup has the right to appoint, after increase in ownership This element represents the number of directors on the board of a company related to the investee company that the reporting entity has the right to appoint, after the increase in stake in the investee company. Number of Directors Company Related to Investee Company Total number of directors on board of Banco de Chile This element represents the total number of directors on the board of a company related to the investee company. Schedule of Guarantee Obligations by Credit Ratings [Table Text Block] Schedule of Guarantor Obligations by Credit Ratings Provides pertinent information about each guarantee obligation, or each group of similar guarantee obligations, by credit ratings, including (a) the nature of the guarantee and (b) the maximum potential amount of future payments (undiscounted) the entity could be required to make under the guarantee. Maturity period of auction rate securities, period one (in days) The period one interval of short maturity auction rate securities used for valuation, based on the observation of auction market prices. The valuation was done based on the observation of auction market prices due to the short maturity period. Auction Market Securities Series Rate Setting Interval Period One Auction Market Securities Series Rate Setting Interval Period Two Maturity period of auction rate securities, period two (in days) The period two interval of short maturity auction rate securities used for valuation, based on the observation of auction market prices. The valuation was done based on the observation of auction market prices due to the short maturity period. This element represents the assumption used for the projected percentage increase (decrease) in housing prices for the third calendar year following the current fiscal year. U.S. housing price percentage increase assumption used, year three and thereafter Housing Price Change Assumptions Future Calendar Year Three and Thereafter Housing Price Change Assumptions Future Calendar Year Four and Thereafter This element represents the assumption used for the projected percentage increase (decrease) in housing prices for the fourth calendar year following the current fiscal year, and all calendar years thereafter. U.S. housing price percentage increase assumption used, year four and thereafter Represents the allowance for credit losses relating to letters of credit and unfunded lending commitments. Allowance for Credit Losses Related to Letters of Credit and Unfunded Lending Commitments Allowance for credit losses relating to letters of credit and unfunded lending commitments Credit Commitments. Credit Commitments [Line Items] Interest Bearing Deposit Liabilities Fair Value Disclosure Interest-bearing deposits This element represents the portion of interest-bearing deposits valued at fair value by the entity. Credit Commitments Credit Commitments Represents the amount of outstanding unused credit commitments made by the entity such as letters of credit, lines of credit and loan commitments. Commercial and Other Consumer Loan Commitments Original Maturity of Less than One Year Commercial and other consumer loan commitments, original maturity of less than one year Represents the amount of outstanding commercial and other consumer loan commitments with an original maturity of less than one year. Auction Market Securities Series Rate Setting Interval Period Three Maturity period of auction rate securities, period three (in days) The period three interval of short maturity auction rate securities used for valuation, based on the observation of auction market prices. The valuation was done based on the observation of auction market prices due to the short maturity period. Schedule of Guarantee Obligations by Expiration Date and Carrying Value [Table Text Block] Schedule of Guarantor Obligations by Expiration Date, Amount Outstanding and Carrying Value Provides pertinent information about each guarantee obligation, or each group of similar guarantee obligations, by expiration date, including (a) the nature of the guarantee, (b) the maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee, and (c) the current carrying amount of the liability, if any, for the guarantor's obligations under the guarantee. Schedule of Credit Commitments [Table Text Block] Schedule of Credit Commitments Provides the amount of outstanding credit commitments by type and location of commitment. Exercise Of Call Options L Q I F [Member] The exercise of call options to increase the stake in LQIF, a wholly owned subsidiary of Quinenco that controls Banco de Chile. LQIF Credit Card Lines of Credit [Member] Represents the credit provided to customers by issuing credit cards. The credit card lines are unconditionally cancellable by the issuer. Credit card lines Commercial and Other Consumer Loan Commitments [Member] Commercial and other consumer loan commitments include overdraft and liquidity facilities, as well as commercial commitments to make or purchase loans, to purchase third-party receivables, to provide note issuance or revolving underwriting facilities and to invest in the form of equity. Commercial and other consumer loan commitments Schedule of Credit Commitments [Table] Tabular disclosure relating to the type of and location of the entity's outstanding credit commitments such as lines of credit, letters of credit and loan commitments. Credit Commitments by Geographic Area [Axis] The geographic areas for which the credit commitment information is being disclosed. Geographic Area for Disclosures [Domain] The entity's home country and other geographic area where there are credit commitments. Credit Commitments by Type of Commitment [Axis] The type of credit commitment for which information is being disclosed. Type of Commitment [Domain] Represents the type of credit commitment. Outside of United States [Member] Geographic area excluding the United States of America. Outside of U.S. New Accounting Pronouncement SFAS 166 and 167 [Member] Adoption of new accounting pronouncements Statement of Financial Accounting Standards 166 and 167. Adoption of SFAS 167 Adoption of SFAS 166 and 167 Commercial Real Estate Construction and Land Development [Member] Commercial real estate, construction and land development include unused portions of commitments to extend credit for the purpose of financing commercial and multifamily residential properties as well as land development projects. Both secured-by-real-estate and unsecured commitments are included, as well as undistributed loan proceeds, where there is an obligation to advance for construction progress payments. Commercial real estate, construction and land development. Fair Value Measurement with Unobservable Inputs Assets Transferred to Level Three from Level Two Transfers from Level 2 to Level 3 This element represents the transfers into Level 3 of assets measured at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes [Table] Summarization of changes in the fair value of assets and liabilities using significant unobservable inputs (Level 3). Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes by Asset Type [Axis] This element provides the group of categories of assets and liabilities for which the change in the balance of the fair value measurement using significant unobservable inputs (level 3) is being disclosed. Changes in the fair value of assets and liabilities related to significant unobservable inputs (Level 3). Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes [Line Items] Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes, Asset Types [Domain] This element provides general categories of assets and liabilities for which the change in the balance of the fair value measurement using significant unobservable inputs (level 3) is being disclosed. Fair Value Measurement With Unobservable Inputs Assets Transferred From Level Three To Level Two This element represents the transfers from Level 3 of assets measured at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Net transfers from Level 3 to Level 2 Fair Value Measurement With Unobservable Inputs Loans Receivable Private Label Consumer Mortgage Securitization Trust Vie Increase (Decrease) In Level Three This element represents the increase (decrease) in the balance of loans receivable related to private label consumer mortgage securitization trust VIEs at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Increase (decrease) in level 3 of loans receivable private label consumer mortgage securitization trust VIE Fair Value Measurement With Unobservable Inputs Loans Receivable Mutual Fund Deferred Sales Commission Vie Increase (Decrease) In Level Three This element represents the increase (decrease) in the balance of loans receivable related to mutual fund deferred sales commission VIEs at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Increase (decrease) in level 3 of loans receivable mutual deferred sales commission VIE Fair Value Measurement With Unobservable Inputs Long Term Debt Private Label Consumer Mortgage Securitization Trust Vie Increase (Decrease) In Level Three This element represents the increase (decrease) in the balance of long-term debt related to private label consumer mortgage securitization trust VIEs at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Increase (decrease) in level 3 of long term debt private label consumer mortgage securitization trust VIE Fair Value Measurement With Unobservable Inputs Long Term Debt Mutual Fund, Deferred Sales Commission Vie Increase (Decrease) In Level Three This element represents the increase (decrease) in the balance of long-term debt related to mutual fund deferred sales commission VIEs at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Increase (decrease) in level 3 of long term debt mutual deferred sales commission VIE Fair Value Measurement With Unobservable Inputs Long Term Debt Collateralized Loan Obligations Vie Increase (Decrease) In Level Three This element represents the increase (decrease) in the balance of long-term debt related to Collateralized Loan Obligations VIEs at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Increase (decrease) in level 3 of long term debt collateralized loan obligation VIE Trust Preferred Securities Issued in Exchange for Senior Notes This element represents the value of trust preferred securities in exchange for the senior notes. Exchanged trust securities for senior notes Impact of Accounting Changes under Fair Value Option [Table Text Block] Impact of accounting changes under fair value option The table showing the impact of change in accounting for Embedded Credit Derivatives to be accounted under fair value option. Fair Value Measurement With Unobservable Inputs Corporate Trading Securities Due To Paydowns And Sales Increase Decrease In Level Three Increase (decrease) in level 3 of corporate trading debt securities due to pay downs and sales This element represents the increase (decrease) in the balance of corporate trading debt securities classified as Level 3 assets, due to pay downs and sales. This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value, and are included in the income statement in principal transactions. Net realized/unrealized gains (losses) included in principal transactions, assets Fair Value Measurement with Unobservable Inputs Reconciliation, Recurring Basis Asset Gain (Loss) Included in Principal Transactions Warrants under Troubled Asset Relief Program and Loss Sharing Agreement [Member] This element represents incremental common shares attributable to warrants issued to U.S. Treasury as part of Troubled Asset Relief Program (TARP) and the loss-sharing agreement that were not included in the computation of diluted earnings per share (EPS). Warrants issued to U.S. Treasury as part of TARP and loss-sharing agreement Investment [Axis] Investment [Domain] Trading Securities and Loans [Member] Trading Securities and Loans Fair Value Measurement with Unobservable Inputs Reconciliation, Recurring Basis Liability Gain (Loss) Included in Other than Principal Transactions This element represents total gains or losses for the period (realized and unrealized), arising from liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value, and are included in the financial statements in locations other than principal transactions. Net realized/unrealized gains (losses) included in locations other than principal transactions, liabilities Fair Value Measurement with Unobservable Inputs Reconciliation, Recurring Basis Liability Gain (Loss) Included in Principal Transactions This element represents total gains or losses for the period (realized and unrealized), arising from liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value, and are included in the income statement in principal transactions. Net realized/unrealized gains (losses) included in principal transactions, liabilities Fair Value Measurement with Unobservable Inputs Reconciliation, Recurring Basis Asset Gain (Loss) Included in Other than Principal Transactions This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value, and are included in the financial statements in locations other than principal transactions. Net realized/unrealized gains (losses) included in locations other than principal transactions, assets Other Asset Backed Securities [Member] Impact of accounting standard update of exception related to embedded credit derivative. Other asset-backed Accounting Standard Update on Embedded Credit Derivative [Member] The impact from a change in accounting for embedded credit derivatives due to ASU 2010-11, Scope Exception Related to Embedded Credit Derivatives, for which the entity selected to account for beneficial interests issued by securitization vehicles under the fair value option at transition on July 1, 2010. Embedded Credit Derivatives Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract] Gross realized investments losses, excluding losses from other-than-temporary impairment Mortgage Backed Securities Default Rate Projection 30 to 59 Day Delinquent This element represents the projected percentage default rate of loans for which the performance is 30-59 day delinquent, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. Default rate projection, loans 30-59 day delinquent (as a percent) Mortgage Backed Securities Default Rate Projection 60 to 90 Day Delinquent This element represents the projected percentage default rate of loans for which the performance is 60-90 day delinquent, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. Default rate projection, loans 60-90 day delinquent (as a percent) Mortgage Backed Securities Default Rate Projection 91 Plus Day Delinquent This element represents the projected percentage default rate of loans for which the performance is 91+ day delinquent, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. Default rate projection, loans 91+ day delinquent (as a percent) Defined Benefit Plan Estimated Future Employer Contributions Direct Payment Estimated employer's future contribution for benefit payments expected to be paid directly by the company Represents the employer's estimate of future contribution for benefit payments expected to be paid directly by the company. Fair Value Measurement with Unobservable Inputs Mortgage Servicing Rights Increase (Decrease) in Level Three Due to Reduction in Interest Rates Increase (decrease) in level 3 of mortgage servicing rights due to reduction in interest rates This element represents the increase (decrease) in the balance of mortgage servicing rights due to reduction in interest rates. Short Term Debt Excluding Intercompany Short-term borrowings Reflects the total carrying amount of debt, excluding intercompany debt, having initial terms less than one year or the normal operating cycle, if longer, as of the balance sheet date for purposes of disclosing consolidating balance sheet information. Long Term Debt Excluding Intercompany long-term debt Including current and noncurrent portions, aggregate carrying amount of long-term borrowings, excluding intercompany long-term borrowings, as of the balance sheet date for purposes of disclosing consolidating balance sheet information. Long-term debt Fair Value Assets Measured on Recurring Basis, Change in Unrealized Gains (Losses) Still Held Unrealized gains (losses) still held, assets This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets). Such unrealized (holding) gains or losses relate to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). Fair Value Liabilities Measured on Recurring Basis, Change in Unrealized Gains (Losses) Still Held Unrealized gains (losses) still held, liabilities This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets). Such unrealized (holding) gains or losses relate to those liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). Available for Sale Securities Continuous Unrealized Loss Position Available-for-sale Securities Continuous Unrealized Loss Position Fair Value and Aggregate Losses [Abstract] Fair Value Measurement With Unobservable Inputs Credit Derivatives Increase (Decrease) In Level Three Increase (decrease) in level 3 of credit derivatives This element represents the increase (decrease) in the balance of credit derivatives classified as Level 3 assets. Fair Value Measurement with Unobservable Inputs Credit Derivatives Settlement Due to Unwind of Contracts Increase (Decrease) in Level Three This element represents the increase (decrease) in the balance of credit derivatives classified as Level 3 assets, due to settlement related to unwind of contracts. Increase (decrease) in level 3 of credit derivatives due to settlement related to unwind of contract Other Non Bank [Member] This element represents the other non-banking industry. Non-bank Alternative Investment Funds Redemption Frequency Alternative investment funds, redemption frequency (if currently eligible) The redemption frequency of alternative investment funds that calculate net asset value per share. Alternative Investment Funds Cost Alternative investment funds, carried at cost Represents the carrying value of funds that carry at cost. Fund Assets Valued by Net Asset Values Provided by Third Party Asset Managers Amount of fund assets valued using net asset values provided by third party asset managers which is included in the total fair value amount of alternative investment funds The amount of fund assets that are valued using NAV (net asset value) provided by third party asset managers is included in total alternative investment fund fair value. Percentage of ownership interest of public shareholders in the Student Loan Corporation (SLC) Percentage of Ownership Interest by Third Party This element represents the percentage of ownership interest of public shareholders in entity's subsidiary. Disposal Group Including Discontinued Operation Purchase of Assets This element represents the purchase of assets by one subsidiary of another, as a part of the disposal group, including a component of the entity (discontinued operation). Purchase of assets by Citibank, N.A from Student Loan Corporation (SLC) Discontinued Operation Gain (Loss) on Disposal Gain or loss after tax expense or benefit, not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale from continuing and discontinued operations. A gain or loss on sale transaction Schedule Of Fair Value Of Short Term Borrowings And Long Term Debt Excluding Debt Issued By Consolidated V I Es [Table Text Block] Represents the schedule of fair value of short-term borrowings and long-term debt, excluding debt issued by consolidated VIEs. Schedule of fair value of long-term debt, excluding debt issued by consolidated VIEs Preferred Stock Series H, Accretion Discount for EPS Calculation Preferred stock Series H discount accretion Preferred stock series H, accretion discount for EPS calculation Represents Student Loan Corporation, an indirect subsidiary. Student Loan Corporation [Member] Student Loan Corporation Represents Discover Financial Services (Discover) and SLM Corporation (Sallie Mae). Discover Financial Services And S L M Corporation [Member] Discover Financial Services (Discover) and SLM Corporation (Sallie Mae) Schedule of Disposal Groups Including Discontinued Operations Student Loan Corporation [Table Text Block] The summarized financial disclosure related to the sale of Student Loan Corporation, which is classified as a discontinued operation. Summarized financial information for Student Loan Corporation Public And Private Preferred Stock Exchange Offer For E P S Calculation This element represents the impact of the public and private preferred stock exchange offer for EPS calculation. Less: Impact of the public and private preferred stock exchange offers Citigroup Capital X I I I [Member] This element represents Citigroup Capital XIII, a trust security with distributions guaranteed by Citigroup. Citigroup Capital XIII Federal Deposit Insurance Corporation [Member] Represents the Federal Deposit Insurance Corporation (FDIC). Federal Deposit Insurance Corporation (FDIC) Debt Instrument Remaining Maturity Amount Remaining maturity amount of debt The remaining maturity amount of long-term debt guaranteed by the FDIC under the TLGP. Private Label Mortgage Backed Securities Issued Value Private label mortgage-backed securities, issued Represents the amount of private label mortgage-backed securities that have been issued. Private Label Mortgage Backed Securities Outstanding Value Private label mortgage-backed securities, outstanding Represents the balance of private label mortgage-backed securitizations from 2005 to 2008 where the Company has no variable interest or continuing involvement as servicer. Securities Transferred To Re Securitization Entities Represents the amount of securities transferred to re-securitization entities. Securities transferred to re-securitization entities Market Value Of Interest In Private Label Re Securitization Entities Market value of interest in U.S. government sponsored agency guaranteed re-securitization entities This element represents the amount of market value of interest owned by the entity in private-label re-securitization entities. Senior Beneficial Interests Obligation reflecting another party's senior right to economic interests in another entity or trust under a contractual right. Senior beneficial interests Subordinated Beneficial Interests Obligation reflecting another party's subordinate right to economic interests in another entity or trust under a contractual right. Subordinated beneficial interests Gain Loss On Sale Of Securities To Re Securitization Entities This element represents the amount of gain or loss recorded on the sale of securities to private-label re-securitization entities. Loss on sale of securities to private-label re-securitization entities Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Liquidation Liquidation that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. Liquidation of Assets Preferred Shares Percentage of Equity Less than The percentage that the preferred shares as a portion of equity are less than, in order to be an insufficient amount of equity. Preferred shares as a percentage of equity, less than Securities reclassified to Trading Securities Reclassified as Trading Assets Represents the amount of securities which are reclassified as Trading. Trading Losses on Derivatives Represents the amount of trading losses on derivatives. Net trading losses on derivatives Fair Value Measurement with Unobservable Inputs Investments Due to Paydowns and Sales This element represents the increase (decrease) in the balance of investments, due to paydowns and sales. Increase (decrease) in investments due to pay downs and sales Losses on Private Equity Investments and Real Estate Fund This element represents the net realized/ unrealized losses recorded in other income due to losses on private equity investments and real estate fund investments Losses on private equity investments and real estate fund Represents U.S. nonqualified pension plans. United States Nonqualified Pension Plans [Member] Nonqualified pension plans Defined Benefit Plan Change in Benefit Obligation Benefits Earned Represents the amount of benefits earned during the period, which results in change in projected benefit obligation. Defined Benefit Plan, Benefits Earned Other Guarantees and Indemnifications [Member] Under other guarantees and indemnifications, entity provides various cardholder protection programs on several of its card products, including programs that provide insurance coverage for rental cars, certain losses associated with purchased products, price protection for certain purchases and protection for lost luggage. Other guarantees and indemnifications Repurchase Reserve Consumer Mortgages Representations and Warranties This element represents the repurchase reserve created for consumer mortgages, representations and warranties. Repurchase reserve for Consumer mortgages representations and warranties Interest cost on benefit obligation Changes in the benefit obligation liability account for defined benefit plans due to interest cost. Defined Benefit Plan, Change in Benefit Obligation Interest Cost Expected Medicare Part D subsidy The amount of the period's gross receipts that are expected from the prescription drug subsidy, which is to be used in the roll forward of the accumulated postretirement benefit obligation of an applicable postretirement benefit plan. Defined Benefit Plan, Gross, Prescription Drug Subsidy Receipts Expected Curtailments Changes in the benefit obligation liability account for defined benefit plans due to curtailments. Defined Benefit Plan, Change in Benefit Obligation Curtailments Investment advisory fees and administrative costs This element represents amount of investment advisory fees and administrative costs that were absorbed by the entity. Defined Benefit Plan, Investment Advisory Fees and Administrative Costs Benefits directly paid by the Company This element represents the amount of benefits that are directly paid by the company. Defined Benefit Plan, Benefits Paid by Employer Plan participants contributions Changes in the fair value of plan assets for defined benefit plans due to participant contributions. Defined Benefit Plan, Change in Fair Value of Plan Assets Contributions by Plan Participants Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract] Net amount recognized Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract] Amounts recognized in Accumulated other comprehensive income (loss) Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets [Abstract] PBO exceeds fair value of plan assets Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets [Abstract] ABO exceeds fair value of plan assets Defined Benefit Plan, Assumptions Used in Calculations [Abstract] Assumptions used in determining pension and postretirement benefit obligations Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] Discount rate Weighted average (as a percent) Represents the weighted average interest rate that is used to adjust for the time value of money for the plan. Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation Discount Rate Weighted Average Future compensation increase rate, Weighted average (as a percent) Represents the expected weighted average rate of compensation increases (for pay-related plans). Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation Weighted Average Rate of Compensation Increase Weighted average (as a percent) Represents the weighted average interest rate that is used to adjust for the time value of money for calculating net periodic benefit cost. Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate, Weighted Average Effect of one-percentage-point change in the discount rates Defined Benefit Plan, Effect of One Percentage Point Change in Discount Rates [Abstract] Effect of one-percentage-point increase in the discount rates The effect of a one-percentage-point increase in the discount rates on pension expenses. Defined Benefit Plan, Effect of One Percentage Point Increase in Discount Rates on Pension Expenses Effect of one-percentage-point decrease in the discount rates The effect of a one-percentage-point decrease in the discount rates on pension expenses. Defined Benefit Plan, Effect of One Percentage Point Decrease in Discount Rates on Pension Expenses Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract] Health-care cost increase rate for U.S. plans Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract] Effect of one-percentage-point change in assumed health-care cost-trend rates Future compensation increase rate, Weighted average (as a percent) Represents the expected weighted average rate of compensation increases for calculating net periodic benefit cost. Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Weighted Average Rate of Compensation Increase Expected long-term rates of return on assets used in determining pension expense Defined Benefit Plan, Assumptions Used Calculating Pension Expenses Expected Long-term Return on Assets [Abstract] Effect of one-percentage-point change in the expected rates of return Defined Benefit Plan Effect of One Percentage Point Change in Expected Rates of Return [Abstract] Effect of one-percentage-point increase in the expected rates of return on pension expense The effect of a one-percentage-point increase in the expected rates of return on pension expenses. Defined Benefit Plan, Effect of One Percentage Point Increase in Expected Rates of Return on Pension Expenses Effect of one-percentage-point decrease in the expected rates of return on pension expense The effect of a one-percentage-point decrease in the expected rates of return on pension expenses. Defined Benefit Plan, Effect of One Percentage Point Decrease in Expected Rates of Return on Pension Expenses Private equity, target asset allocation minimum range (as a percent) Target allocation minimum percentage of investments in private equity to total plan assets that is presented on a weighted-average basis, as of the measurement date of the latest statement of financial position. Defined Benefit Plan, Target Allocation Percentage of Assets Private Equity Range Minimum Private equity, target asset allocation maximum range (as a percent) Target allocation maximum percentage of investments in private equity to total plan assets that is presented on a weighted-average basis as of the measurement date, of the latest statement of financial position. Defined Benefit Plan, Target Allocation Percentage of Assets Private Equity Range Maximum Private equity (as a percent) The percentage of the fair value of private equity to the fair value of total plan assets that are held as of the measurement date. Defined Benefit Plan Private Equity Represents investment in mutual funds Mutual Funds [Member] Mutual Funds Defined Benefit Plan Fair Value of Plan Assets [Roll Forward] Reconciliations of the beginning and ending balances during the period for Level 3 assets Equity Securities U S [Member] U.S. equity Equity Securities Non U S [Member] Non-U.S. equity Defined Benefit Plan, Weighted Average Asset Allocation Percentage of Assets Debt Securities Debt securities, weighted-average asset allocation (as a percent) The percentage of the fair value of debt securities to the fair value of total plan assets that are held as of the measurement date. Defined Benefit Plan, Weighted Average Asset Allocation Percentage of Assets Real Estate The percentage of the fair value of real estate to the fair value of total plan assets that are held as of the measurement date. Real estate, weighted-average asset allocation (as a percent) Equity securities, weighted-average asset allocation (as a percent) The percentage of the fair value of equity securities to the fair value of total plan assets that are held as of the measurement date. Defined Benefit Plan Weighted Average Asset Allocation Percentage of Assets Equity Securities The estimated future benefit payments without the effect of the subsidy in year 5. 2015 Defined Benefit Plan, Expected Future Benefit Payments before Subsidy in Year Five Defined Benefit Plan Expected Future Benefit Payments before Subsidy in Five Fiscal Years Thereafter The amount of aggregate estimated future benefit payments without the effect of the subsidy in five fiscal years thereafter (the aggregate amount of benefits expected to be paid in years 6 through 10 after the date of the latest statement of financial position). 2016-2020 Defined Benefit Plan, Weighted Average Asset Allocation Percentage of Assets Other Other investments, weighted-average asset allocation (as a percent) The percentage of the fair value of other investments to the fair value of total plan assets that are held as of the measurement date. Defined Benefit Plan, Expected Future Benefit Payments before Subsidy in Year One 2011 The estimated future benefit payments without the effect of the subsidy in year 1. Defined Benefit Plan, Expected Future Benefit Payments before Subsidy in Year Two The estimated future benefit payments without the effect of the subsidy in year 2. 2012 Defined Benefit Plan, Expected Future Benefit Payments before Subsidy in Year Three The estimated future benefit payments without the effect of the subsidy in year 3. 2013 Defined Benefit Plan, Expected Future Benefit Payments before Subsidy in Year Four The estimated future benefit payments without the effect of the subsidy in year 4. 2014 Defined Benefit Plan, Estimated Future Benefit Payments [Abstract] Estimated Future Benefit Payments Postretirement Medical Plans with Prescription Drug Benefits [Abstract] Expected U.S. postretirement benefit payments Before Medicare Part D subsidy Disclosure of Expected Gross Prescription Drug Subsidy Receipts [Abstract] Expected U.S. postretirement benefit payments Medicare Part D subsidy Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract] Defined Contribution Pension and Other Postretirement Plans Disclosure Change in Accumulated Other Comprehensive Income (Loss) Due to Deferred Taxes Represents the amount of change in Accumulated other comprehensive income (loss) due to deferred taxes. Change in deferred taxes, net Change in Accumulated Other Comprehensive Income (Loss) Due to Amortization and Other Represents the amount of change in Accumulated other comprehensive income (loss) due to amortization and other. Net amortizations Defined Contribution Plan, Employer Contribution Matching Percent of Eligible Compensation The percentage of matching contribution made by the employer to a defined contribution plan for participating employees during the period. Maximum percentage contribution by employer of employees eligible pay Defined Contribution Plan Fixed Percentage Employer Contribution for Eligible Employees Represents the percentage of fixed contribution for eligible employees whose compensation is 100,000 or less. Percentage of fixed contribution by employer, for eligible employees whose compensation is $100,000 or less United States Qualified Pension Plans [Member] Represents U.S. qualified pension plans. United States Qualified Pension Plans U S Pension And Postretirement Benefit Plans [Member] Represents U.S. pension and postretirement benefit plans. U.S. pension and postretirement benefit plans Non U S Pension And Postretirement Benefit Plans [Member] Represents non-U.S. pension and postretirement benefit plans. Non-U.S. pension and postretirement benefit plans Schedule of Changes in Projected Benefit Obligations and Changes in Fair Value of Plan Assets [Table Text Block] Disclosure of the change in the benefit obligation and fair value of the assets of pension plans from the beginning to the end of the period, showing separately, if applicable, the effects of the following: service cost, interest cost, contributions by plan participants, actuarial gains and losses, foreign currency exchange rate changes, benefits paid, plan amendments, business combinations, divestitures, curtailments, settlements, and special and contractual termination benefits. Net Amount Recognized Schedule of Changes in Accumulated Other Comprehensive Income [Table Text Block] Disclosure of the changes in accumulated other comprehensive income due to benefit cost. Change in Accumulated other comprehensive income (loss) Schedule of Projected Benefit Obligation and Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block] Disclosure of projected benefit obligation, accumulated benefit obligations and fair values of plan assets of pension plans and/or other employee benefit plans where the projected benefit obligation and accumulated benefit obligation exceeds the fair value of plan assets. Aggregate projected benefit obligation, accumulated benefit obligation and fair value of plan assets for pension plans with PBO in excess of plan assets and ABO in excess of plan assets Assumption used in determining net benefit expense Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Share Based Compensation Arrangements By Share Based Payment Award, Plan Name [Domain] Information pertaining to the various equity-based compensation plans under the share-based compensation arrangement. Share-based Compensation Arrangements by Share-based Payment Award, Plan Name [Domain] Schedule Of Share Based Compensation Arrangement By Share Based Payment Award, Award [Axis] This element represents the details that pertain to the type of share-based compensation awards. Schedule Of Share Based Compensation Arrangement By Share Based Payment Award, Award [Domain] This element represents the details that pertain to the various types of instruments of the share-based compensation awards. Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award [Domain] Schedule of Effect of One Percentage Point Change in Discount Rates on Pension Expense [Table Text Block] Disclosure of the effect of a one-percentage-point increase and the effect of a one-percentage-point decrease in the discount rate on the pension expenses. Effect of one-percentage-point change in the discount rates on pension expense Schedule Of Expected Long Term Rates Of Return On Assets [Table Text Block] Disclosure of the expected long-term rates of return on assets used in determining the Company's pension expense. Expected long-term rates of return on assets Schedule Of Effect Of One Percentage Point Change In Expected Rates Of Return [Table Text Block] Disclosure of the effect of a one-percentage-point increase and decrease in the expected rates of return on the pension expenses. Effect of one-percentage-point change in the expected rates of return on pension expense Schedule of Fair Value of Plan Assets by Measurement Levels [Table Text Block] Disclosure of fair value of plan assets of pension plans and/or other employee benefit plans by level within the fair value hierarchy in which the fair value measurements fall, segregating the fair value measurements using quoted prices in active markets for identical assets or liabilities (Level 1), significant other observable inputs (Level 2) and significant unobservable inputs (Level 3). Plan assets by detailed asset categories and the fair value hierarchy Stock Award Programs [Member] This element represents the Stock Award Program, which forms a part of the entity's incentive plans. Stock Award Programs Capital Accumulation Program Awards [Member] This element represents the Capital Accumulation Program (CAP). Capital Accumulation Program Awards (CAP) Share-based Compensation [Abstract] Components of compensation expense Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Unvested stock awards, weighted average award issuance fair value Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Weighted-average exercise price Share-based Compensation Arrangement by Share-based Payment Award, Options Intrinsic Value Per Share [Abstract] Intrinsic value per share Share-based Compensation Arrangement by Share-based Payment Award, Assumptions Information for Options [Abstract] Assumption information for option programs Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Valuation assumptions Deferred Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Income Tax Effects Allocated Directly to Equity [Abstract] Income tax expense (benefit) reported in stockholders' equity related to: Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Tax Taxes related to the amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting. Provision (benefit) for effect of OTTI losses Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract] Reconciliation of the federal statutory income tax rate to the Company's effective income tax rate applicable to income from continuing operations (before noncontrolling interests and the cumulative effect of accounting changes) Components of Deferred Tax Assets [Abstract] Deferred tax assets Deferred Tax Assets, Undistributed Foreign Earnings Unremitted foreign earnings This element represents tax effects as of the balance sheet date of the estimated future tax effects attributed to unremitted earnings of subsidiaries and other recognized entities in countries outside the country of domicile which will decrease future taxable income when such earnings are distributed into the country of domicile. Deferred Tax Assets, Tax Investments Investment and loan basis differences The tax effect as of the balance sheet date of the amount of the estimated future tax deductions arising from the gain or loss incurred on investments and loans. Schedule of Income Tax Penalties and Interest Accrued [Table Text Block] Schedule of interest and penalties included in the provision for income taxes Disclosure of changes in the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties. Schedule of Deferred Tax Assets and Liabilities by Jurisdiction [Table Text Block] Schedule of deferred tax assets and liabilities by jurisdiction Disclosure of components of net deferred tax asset or liability by the applicable tax jurisdiction or component. Summary of Tax Carryforwards [Table Text Block] Summarization of amounts of tax carryforwards and their expiration dates Disclosure of tax carryforwards by expiration date. Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Current Deferred Tax Assets, Tax Credit and Operating Loss Carryforwards The sum of the tax effects as of the balance sheet date of the amount of excesses of tax deductions over gross income in a year which cannot be used on the tax returns in the current year but can be carried forward to reduce taxable income or income taxes payable in a future year and future tax deductions arising from all unused tax credit carryforwards which have been reduced by a valuation allowance. Tax credit and net operating loss carryforwards Foreign pretax earnings from discontinued operations Income (Loss) from Discontinued Operations before Income Taxes, Foreign The portion of earnings or loss from discontinued operations before income taxes that is attributable to foreign operations, which is defined as income or loss generated from operations located outside the entity's country of domicile. Expiration Date [Axis] Represents expiration dates of foreign tax credits which are available to be carried forward. Expiration Date [Domain] Represents expiration dates of operating loss carryforwards. This element represents the expiration date of operating loss carryforwards and tax credit carryforwards in 2016. Expiration Date 2016 [Member] 2016 This element represents the expiration date of operating loss carryforwards and tax credit carryforwards in 2017. Expiration Date 2017 [Member] 2017 This element represents the expiration date of operating loss carryforwards and tax credit carryforwards in 2018. Expiration Date 2018 [Member] 2018 This element represents the expiration date of operating loss carryforwards and tax credit carryforwards in 2019. Expiration Date 2019 [Member] 2019 Components of Deferred Tax Liabilities [Abstract] Deferred tax liabilities Deferred Tax Liabilities, Credit Valuation Adjustment on Debt Issued Credit valuation adjustments on company-issued debt The amount as of the balance sheet date of the estimated future tax effects attributable to credit valuation adjustments on the debt issued by the reporting entity. Unrecognized Tax (Benefits), Increase (Decrease) Resulting from Foreign Exchange Gain (Loss) on Acquisitions and Dispositions The gross amount of increases or decreases in unrecognized tax benefits resulting from the foreign exchange impact related to acquisitions and dispositions by the entity during the reporting period. Foreign exchange, acquisitions and dispositions Expiration Date 2029 [Member] 2029 This element represents the expiration date of operating loss carryforwards and tax credit carryforwards in 2029. This element represents the expiration date of operating loss carryforwards and tax credit carryforwards between 2012 and 2030. Expiration Date 2012 to 2030 [Member] 2012-2030 Operating Loss and Tax Credit Carryforwards [Line Items] Operating loss and tax credit carryforwards Deferred Tax Assets, Operating Loss Carryforwards, New York Local The tax effect as of the balance sheet date of the amount of excess of tax deductions over gross income in a year which cannot be used on the tax return of a New York Local jurisdiction in the current year but can be carried forward to reduce taxable income or income taxes payable in a future year, for which there must be sufficient tax-basis income to utilize a portion or all of the carryforward amount to realize the deferred tax asset. Total New York City NOL carryforwards Deferred Tax Assets, Operating Loss Carryforwards, Indefinitely Invested Foreign Subsidiaries Accumulated Undistributed Earnings This element represents the tax effect of the balance sheet date of the amount of excess of tax deductions over gross income in a year which cannot be used on the tax return, relating to unrepatriated foreign earnings, for which deferred taxes have been provided even though they are considered to be permanently reinvested abroad, as of the balance sheet date. Deferred tax assets for foreign subsidiaries where earnings are indefinitely reinvested, net operating loss carryforwards Deferred Tax Liabilities to be Reversed Included in Net Deferred Tax Assets This element represents the deferred tax liability included in net deferred tax assets that will reverse in relevant carryforward period. DTLs that will reverse in the relevant carryforward period Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense [Abstract] Interest and penalties included as a component of the Provision for income taxes Unrecognized Tax Benefits, Foreign Income Tax Penalties Accrued This element represents the amount of statutory penalties accrued under foreign tax laws as of the date of the statement of financial position for a tax position claimed or expected to be claimed by the entity, in tax return, that does not meet minimum statutory threshold to avoid payment of penalties. Foreign penalties included in total interest and penalties in the balance sheet This element represents the expiration date of operating loss carryforwards and tax credit carryforwards in 2028. Expiration Date 2028 [Member] 2028 Domestic Losses Reclassified as Foreign Source Income This element represents domestic losses reclassified as foreign source income which is sufficient to cover foreign tax credits being carried forward. Domestic losses allowed to be reclassified as foreign source income Domestic Losses Reclassified as Foreign Source Income Limit This element represents the limit on domestic losses to be reclassified as foreign source income as a percentage of domestic source income generated in subsequent years. Limit on domestic losses to be reclassified as foreign source income (as a percent) Deferred Tax Assets, Utilization Cumulative Ownership Change Percentage This element represents the cumulative percentage change in the shareholders' ownership to constitute an ownership change which will affect the ability of the entity to utilize its deferred tax assets. Cumulative percentage changes in shareholders' ownership to constitute ownership change Deferred Tax Assets, Utilization Ownership Change, Minimum Basis Percentage Increase This element represents the minimum basis percentage increase in the shareholders' ownership in the specified rolling period. Minimum basis percentage points, increase Deferred Tax Assets, Utilization Ownership Change Rolling Period This element represents the rolling period over which the basis percentage increase in the shareholders' equity is measured for the purpose of calculating the 'ownership change' as defined in section 382 of the Internal Revenue Code of 1986, as amended, which will affect the ability of the entity to utilize its deferred tax assets. Rolling period for measuring the percentage points increase (in years) Deferred Tax Assets, Compensation Deductions This element represents the compensation deductions included in deferred tax assets for which no adjustment was permitted in tax laws. Compensation deductions included in DTAs Deferred Tax Assets, Tax Credit Carryforwards Income Necessary to Realize, Deferred Tax Assets This element represents the amount of income necessary to fully realize federal, state and local deferred tax assets. Amount of taxable income necessary to fully realize U.S. federal, state and local DTAs Deferred Tax Assets, Tax Credit Carryforwards Foreign Period This element represents the period of expiration of foreign deferred tax assets carryforwards. U.S. foreign tax credit carryforward period (in years) Deferred Tax Assets, Tax Credit Carryforwards, Foreign Utilization Limit This element represents the limit on the utilization of foreign tax credits as a percentage of foreign source taxable income. Limit on utilization of foreign tax credit carryforwards (as a percent) Percentage of Allocable Interest in Trust Represents the percentage of the allocable interests of investment commingled in a trust. Allocable interest (as a percent) Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract] Amounts that will be amortized from Accumulated other comprehensive income (loss) into net expense in next fiscal year Percentage of Plan Assets Represents percentage of plan assets. Percentage of plan assets Deferred Tax Assets Intangibles The tax effect as of the balance sheet date of the amount of the estimated future tax deductions attributable to intangibles related items which can only be realized if sufficient taxable income is available. Intangibles Deferred Tax Liabilities, Investments Investments The amount as of the balance sheet date of the estimated future tax effects attributable to the gain or loss incurred on investments. Deferred Tax Liabilities, Deferred Policy Acquisition Costs and Value of Insurance in Force Deferred policy acquisition costs and value of insurance in force The amount as of the balance sheet date of the estimated future tax effects attributable to deferred policy acquisition costs and the value of insurance in force. Deferred Tax Assets, Net Operating Loss Carryforwards, New York State Total New York State NOL carryforwards The net tax effect as of the balance sheet date of the amount of excess of tax deductions over gross income in a year which cannot be used on the tax return of a New York state jurisdiction in the current year but can be carried forward to reduce taxable income or income taxes payable in a future year, for which there must be sufficient tax-basis income to utilize a portion or all of the carryforward amount to realize the deferred tax asset. Represents information pertaining to the reporting entity's stake in Nikko Asset Management. Nikko Asset Management [Member] Nikko Asset Management Repayment of Structured Debt Represents the amount of net terminations of structured notes. Net terminations of structured notes Repurchase of structured notes issued by Lehman entities No Expiration Date [Member] This element represents operating loss carryforwards and tax credit carryforwards without any expiration date. No Expiration Date Deferred Tax Assets, Tax Deferred Expense Reserves and Accruals Restructuring Charges and Settlement The amount as of the balance sheet date of the estimated future tax deductions arising from estimates of restructuring reserve costs and settlements, which can only be deducted for tax purposes when restructuring charges are actually incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Restructuring and settlement reserves Fixed assets and leases Deferred Tax Liabilities, Property Plant and Equipment and Leases The amount as of the balance sheet date of the estimated future tax effects attributable to the difference between the tax basis of capital assets and leases and the basis of capital assets and leases computed in accordance with generally accepted accounting principles. The difference in basis, attributable to different capitalization of costs, depreciation, or amortization methodologies, will increase future taxable income when such basis difference is realized. Other Intangible Assets, Additions This element represents additions to other intangible assets during the year. Additions to other intangibles Unaffiliated Borrower Short Term Financial Facility Guaranteed Represents amount guaranteed by City group out of amount drawn down under committed financing from unaffiliated borrower. Guarantee for committed financing with an unaffiliated bank Weighted Average Coupon Rate Represents the weighted average coupon rate of the long-term debt. Weighted average coupon (as a percent) Debt Instrument, Weighted Average Interest Rate after Effect of Derivative Contract Represents the weighted average interest rate at the end of the period after the effect of the derivative contract. Overall weighted average interest rate for long-term debt including effects of derivative contracts (as a percent) Long-term Debt, by Maturity [Abstract] Aggregate annual maturities of long-term debt obligations Citigroup Global Markets Limited [Member] This element represents the Citigroup Global Markets Limited, a subsidiary of the entity. Citigroup Global Markets Limited Tier One Leverage Capital Required to be Well Capitalized to Average Assets for Bank Holding Company The amount of Tier 1 Leverage Capital required, for bank holding company, to be categorized as well capitalized divided by average assets as defined in the regulatory framework for a prompt corrective action. Well-capitalized minimum leverage ratio for bank holding companies (as a percent) Securities Sold under Agreements to Repurchases and Other Assets Pledged, Fair Value [Abstract] Approximate fair values of securities sold under agreements to repurchase and other assets pledged Securities Sold under Agreements to Repurchase, Fair Value Disclosure before Netting For securities sold under agreements to repurchase This element represents the fair value of securities that an institution sells and agrees to repurchase (seller-borrower) at a specified date for a specified price, excluding the impact of any reductions, offsets or nettings. Assets Pledged as Collateral for Securities Borrowed, Fair Value Disclosure This element represents the fair value of collateral for securities borrowed for approximately equivalent value. As collateral for securities borrowed for approximately equivalent value Assets Pledged as Collateral for Bank Loans, Fair Value Disclosure As collateral on bank loans This element represents the fair value of other assets pledged as collateral for bank loans. Collateral Held on Reverse Repurchase Agreements to Clearing Organizations or Segregated under Securities Exchange Commission Regulation, Fair Value Disclosure To clearing organizations or segregated under securities laws and regulations This element represents the fair value of assets pledged as collateral to clearing organizations or segregated under securities' laws and regulations. Assets Pledged as Collateral for Securities Loaned, Fair Value Disclosure For securities loaned This element represents the fair value of other assets pledged as collateral for securities loaned. Assets Pledged as Collateral Other, Fair Value Disclosure Other This element represents the fair value of assets pledged as collateral for other borrowings not separately reported. Securities Sold under Agreements to Repurchase and Other Assets Pledged, Fair Value This element represents the fair value of assets pledged and securities sold under an agreement to repurchase. Securities sold under agreements to repurchase and other assets pledged, total Cash and Securities Segregated under Securities Exchange Commission and Other Regulation, Fair Value Disclosure Cash segregated under federal and other brokerage regulations included in cash and due from banks This element represents the fair value of assets pledged as collateral that are covered under federal and other brokerage regulations. Leases, Operating [Abstract] Lease Commitments Guarantees of Collection of Contractual Cash Flows [Member] Guarantees of collection of contractual cash flows to protect investors in credit card receivables securitization trusts from the loss of interest relating to insufficient collections on the underlying receivables in trusts. Guarantees of collection of contractual cash flows Schedule of Fair Value of Assets Pledged [Table Text Block] Approximate fair values of securities sold under agreements to repurchase and other assets pledged, excluding the impact of allowable netting Disclosure of the fair value of assets pledged and securities sold under agreements to repurchase. Operating Loss and Tax Credit Carryforwards [Table] Schedule reflecting pertinent information, such as tax authority, amounts, and expiration dates, of net operating loss carryforwards and tax credits, including an assessment of the likelihood of utilization. Operating Leases, Future Minimum Payments Due [Abstract] Future minimum annual rentals under noncancelable leases, net of sublease income Life Insurance and Annuity Business [Member] Represents information pertaining to Citi Group's Travelers Life and Annuity and substantially all of Citigroup's international insurance businesses. Life insurance and annuity business Commercial and Similar Letter of Credit [Member] Represents the irrevocable undertaking to guarantee payment of specified commercial and similar obligation if defined events occur or fail to occur. Commercial and similar letters of credit Egg Banking Plc [Member] Represents the acquired business of Egg Banking plc. Egg Banking PLC Akbank [Member] Represents the acquired business of Akbank. Akbank Disposal Group Percentage of Ownership in Disposed Company Represents the percentage of ownership in an entity of which the reporting entity disposed, prior to the disposition. Percentage of ownership in disposed entity Represents information pertaining to the reporting entity's interest in Phibro LLC. Phibro LLC [Member] Phibro LLC Represents information pertaining to the reporting entity's ownership in Nikko Citi Trust and Banking Corporation. Nikko Citi Trust and Banking Corporation [Member] Nikko Citi Trust and Banking Corporation Represents information pertaining to the reporting entity's Financial Institutions (FI) and Diners Club North America credit card businesses. Citigroup Sold Its Financial Institutions F Iand Diners Club North America Credit Card [Member] Citigroup's FI and Diners Club North America credit card businesses Represents the disposed of business of joint venture with Morgan Stanley. Morgan Stanley [Member] Joint Venture with Morgan Stanley Citigroup Technology Services Limited [Member] Represents the disposed of business of Citigroup Technology Services Limited. Citigroup Technology Services Limited Upromise Cards Portfolio [Member] Represents the disposed of business of Upromise Cards Portfolio. Upromise Cards Portfolio Represents the disposed of business of CitiStreet. Citi Street [Member] CitiStreet Represents the disposed of business of Diners Club International. Diners Club International [Member] Diners Club International The amount of credit card receivables disposed of as part of the disposal of credit card businesses or portfolios. Credit card receivables disposed of as part of the disposal of credit card businesses or portfolios Disposal Group Credit Card Receivables The aggregate amount of a process outsourcing agreement made with the purchaser of a business of which the reporting entity disposed. Amount of outsourcing services agreement Outsourcing Services Agreement, Amount The period of time covered by a process outsourcing agreement made with the purchaser of a business of which the reporting entity disposed, as stated in years. Period of outsourcing services agreement (in years) Outsourcing Services Agreement, Period Devaluation of Venezuelan Bolivar [Member] Represents the effect of Venezuelan Bolivar devaluation. Venezuelan Bolivar Devaluation Net, Monetary Assets at Official Rate Represents the amount of net monetary assets denominated in bolivars and subject to the official rate. Citigroup's net monetary assets at the official rate Represents the foreign currency exchange rate before devaluation. Official foreign currency exchange rate before devaluation (in bolivars) Foreign Currency Exchange Rate before Devaluation Foreign Currency Exchange, Rate after Devaluation Represents the foreign currency exchange rate after devaluation. Official foreign currency exchange rate after devaluation (in bolivars) Foreign Currency Subsidized Exchange Rate Represents the foreign currency subsidized exchange rate for the importation of certain essential goods. Subsidized foreign currency exchange rate (in bolivars) Foreign Currency, Devaluation Loss Pretax Represents the pretax loss due to foreign currency devaluation. Pretax loss due to foreign currency devaluation Allowance for Loan and Lease Losses Net Losses Recoveries Reflects the amount of loans and leases that have been removed or charged off from both loan receivables and the reserve for credit losses, net of any recoveries of previously removed or charged off credit losses. Net credit losses (NCLs) Loans and Leases Receivable, Reserve Builds or Releases, Net Reflects the balance sheet activity during the period for the amount charged against earnings for credit losses on loans and leases receivable that are expected and were collectively evaluated for impairment. Net reserve builds (releases) Net reserve releases Allowance for credit losses on unfunded lending commitments at end of period Unfunded Lending Commitments Allowance for Credit Losses The reserve to cover probable credit losses related to unfunded lending commitments as of the balance sheet date. Allowance for credit losses on unfunded lending commitments at beginning of period Loans and Leases Receivable and Unfunded Lending Commitments Allowance The reserve to cover probable credit losses related to loans and leases receivable and unfunded lending commitments as of the balance sheet date. Total allowance for loans, leases, and unfunded lending commitments at end of period Schedule of Loans and Leases Receivable, Allowance for Credit Losses [Table] Schedule detailing information related to loan and lease receivables allowance for credit losses. Loans and Leases Receivable, Allowance [Domain] Loans and leases receivable allowance account by explanation group. Represents the securitizations. Securitizations [Member] Securitizations U S Real Estate Lending Loans [Member] Represents the sale or transfers to held-for-sale of U.S. Real Estate Lending Loans. U.S. Real Estate Lending Loans Represents the transfer of the U.K. Cards portfolio to held-for-sale. U K Cards Portfolio To Held For Sale [Member] U.K. cards portfolio to held-for-sale Loans and Leases Receivable, Specific Reserve Builds or Releases, Net Reflects the balance sheet activity during the period for the amount charged against earnings for credit losses on loans and leases receivable that are expected and were individually evaluated for impairment. Net specific reserve builds (releases) Net specific reserve builds Loans and Leases Receivable, Allowance for Credit Losses Other, Net Represents the net amount of other allowances for credit losses related to loan and lease receivables. Other, net Other Other, net Unfunded Lending Commitments Allowance for Credit Losses [Roll Forward] Allowance for credit losses on unfunded lending commitments Represents the FX Translation. F X Translation [Member] FX translation Loans and Leases Allowance for Credit Losses [Line Items] Allowance for loan losses disclosures Number of Investments where Cost Exceeded Fair Value as of Reporting Date The number of investments where their cost exceeded their fair value as of the reporting date. Number of securities where their cost exceeded their fair value (in quantity) Percentage of Fixed Income Investments in Gross Unrealized Loss Less than Year This element represents the percentage of fixed-income investments that have been in a gross unrealized loss position for less than a year and were rated investment grade. Percentage of fixed-income investments in gross-unrealized-loss position for less than a year that were rated investment grade If aggregate disclosures are presented, the aggregate benefit obligation for plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented. Accumulated benefit obligation Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets Accumulated Benefit Obligation Defined Benefit Plan Weighted Average Target Asset Allocations The aggregate weighted average percentage of the fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of total plan assets held as of the measurement date. Total (as a percent) Defined Benefit Plan Actual Return on Plan Assets Realized Gains (Losses) This element represents the realized gains (losses) on plan assets of pension plans and/or other employee benefit plans for the period. Realized gains (losses) Defined Benefit Plan Actual Return on Plan Assets Unrealized Gains (Losses) This element represents the unrealized gains (losses) on plan assets of pension plans and/or other employee benefit plans for the period. Unrealized gains (losses) Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit Related Interest The amount of the interest associated with the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date. Gross interest related to gross uncertain tax positions for items expected to be resolved in next 12 months Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Tax Benefit to Continuing Operations, Upper Bound The estimated upper bound of the tax benefit to continuing operations that is reasonably possible related to a change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken. Potential tax benefit to continuing operations from gross uncertain tax positions expected to be resolved in next 12 months Deferred Tax Assets by Jurisdiction [Table] A listing of components of net deferred tax asset or liability by the applicable tax jurisdiction or business component. Percentage of Fixed Income Investments in Gross Unrealized Loss for Year or More This element represents the percentage of fixed-income investments in rated investment grade that have been in a gross unrealized loss position for a year or more. Percentage of fixed-income investments in gross-unrealized-loss position for a year or more, rated investment grade Deferred Tax Assets by Jurisdiction [Axis] Description and amount of deferred tax assets by tax jurisdiction or business component. Deferred Tax Assets by Jurisdiction [Domain] New York [Member] The designated tax department of the New York government entitled to levy and collect income taxes from the entity. New York Schedule of Income Tax Expense (Benefit), Intraperiod Tax Allocation [Table Text Block] Disclosure of the allocation of income tax expense or benefit for the period between continuing operations, discontinued operations, extraordinary items, other comprehensive income, and items charged or credited directly to shareholders' equity. Schedule of reconciliation of income tax expense (benefit) Gain (Loss) on Investments Tax This item represents the tax effect included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain or loss of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain or loss which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Provision (benefit) for effect of securities transactions Deferred Tax Liabilities Interest Interest related items The cumulative amount of the estimated future tax effects attributable to interest related temporary differences that were expensed for tax purposes but capitalized in conformity with generally accepted accounting principles. Total interest and penalties in the consolidated balance sheet at the beginning of the period, net of tax Total interest and penalties in the consolidated balance sheet at the end of the period, net of tax Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Net of Tax This element represents the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties, net of resulting tax. Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Net of Tax This element represents the total of interest expense recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties in the period in which the entity claims or expects to claim a tax position, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties, net of related tax. Total interest and penalties in the consolidated statement of income, net of tax Other State [Member] The designated tax department of all state governments not otherwise specified, entitled to levy and collect income taxes from the given entity. Other state Financing Receivables Carrying Amount [Table Text Block] Disclosure of the carrying amount of loans and lease receivables as of the balance sheet date, net of deferred income. Schedule of financing receivables Loans Acquired in Transfer Accounted for as Debt Securities Activity [Table Text Block] Disclosure of loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Schedule of changes in the accretable yield, related allowance and carrying amount, net of accretable yield Deferred Tax Assets by Jurisdiction [Line Items] Deferred tax assets by jurisdiction Deferred Tax Assets, Future Tax Deductions and Credits The tax effect as of the balance sheet date of the amount of estimated future tax deductions and credits arising from temporary differences. Future Tax Deductions and Credits Deferred Tax Assets, Tax Credit Carryforwards, Federal State and Local Period This element represents the period of expiration of federal, state, and local deferred tax assets carryforwards. U.S. Federal and New York State and City NOL carryforward period (in years) Financing Receivables by Geographical Area [Axis] Represents financing receivables with reference to geographical area. Financing Receivables by Geographical Area [Domain] Represents the bifurcation of loans and lease receivables by geographical area. Represents loans and lease receivables from entities belonging to domestic countries. Financing Receivables Domestic Country [Member] In U.S. offices Represents loans and lease receivables from entities belonging to a country other than domestic country. Financing Receivables Foreign Countries [Member] In offices outside the U.S. Represents financing receivables classified as corporate loans. Corporate Loan [Member] Corporate Represents financing receivables classified as installment and other loans. Installment and Other [Member] Installment and other Installments Revolving Credit and Other [Member] Represents financing receivables classified as installment, revolving credit and other. Installment, revolving credit and other Represents the commercial and industrial loan. Commercial and Industrial [Member] Commercial and industrial Represents financing receivables classified as lease financing. Lease Financing [Member] Lease financing Represents financing receivables from financial institutions. Loans to Financial Institutions [Member] Loans to financial institutions Government and Official Institutions [Member] Represents financing receivables from government and official institutions. Government and official institutions Loans and Leases Receivable, Gross Carrying Amount [Line Items] Loans Impaired Financing Receivable Unpaid Principal Balance [Abstract] Impaired financing receivable unpaid principal balance Financing Receivable Modifications Post 2007 The dollar amount as of the end of the period for smaller-balance impaired consumer loans modified since January 1, 2008. Smaller-balance impaired consumer loans modified since January 1, 2008, dollar amount Repurchase Reserve Additions for New Sales Additions for new sales Represents the amount of addition to repurchase reserve for new sales of mortgage loans. Repurchase Reserve Change in Estimate Change in estimate Represents the amount of change in the estimate of repurchase reserve due to an impact of macroeconomic factors and recent experience. Repurchase Reserve Utilizations Utilizations Represents the amount of utilizations of repurchase reserve. Other than Temporary Impairments on Investment Securities [Abstract] Other-than-temporary impairments on investment securities Activity in the repurchase reserve Repurchase Reserve [Roll Forward] Balance, beginning of the year Balance, end of the year Repurchase Reserve Represents the amount of repurchase reserve for mortgage loans repurchase in the event of a breach of representations and warranties. Cumulative Effect of Initial Adoption of New Accounting Principle before Tax Cumulative effect on retained earnings, pretax Cumulative effect of initial adoption of new accounting principle on the opening balance of retained earnings, before tax. Percentage of Fair Value of All Assets and Liabilities of Acquirer Represents the percentage of step-up to fair value for all assets and liabilities acquired in a business combination. Percentage of step-up to fair value for all assets and liabilities acquired Representations and Warranties [Abstract] Representations and warranties Percentage of Interest Acquired in Business Combinations for Goodwill Valuation Represents the percentage of acquisition assumed for valuation of goodwill in a business combination. Percentage of acquisition assumed for valuation of goodwill Noncontrolling Interests in Subsidiaries [Abstract] Noncontrolling interests in subsidiaries Reclassification of Noncontrolling Interests from Other Liabilities to Stockholders Equity Represents the amount of noncontrolling interests reclassified from other liabilities to stockholders' equity due to adoption of ASC 810-10-45-15. Noncontrolling interests reclassified from other liabilities to Total equity Revisions to Earnings Per Share Calculation [Abstract] Revisions to the Earnings-per-Share Calculation Reported Earnings Per Share, Basic Represents the reported value of basic earnings per share. As reported (in dollars per share) Reported Earnings Per Share, Diluted Represents the reported value of diluted earnings per share. As reported (in dollars per share) Schedule of Activity in Repurchase Reserve [Table Text Block] Tabular disclosure of activity in the repurchase reserve for the year. Activity in the repurchase reserve Dollar amount of loans included under Citi's short-term modification programs Amount Under Citi Short Term Modification Programs The dollar amount of loans included under Citi's short-term modification programs at the end of the period. Maximum Period Of Modification Under Citi Short Term Programs The maximum period of loan modification under Citi's short-term modification programs (in months) Maximum period of loan modification under Citi's short-term modification programs (in months) Financial Instruments Policies [Table] These elements list the policy of the entity regarding the period for interest accrual on loans. Financial Instruments [Axis] Pertinent information about loans' interest accrual period. Types of Financial Instruments: [Domain] Types of financial instruments typically securitized, transferred, or serviced. Installment and Real Estate Loans [Member] Represents the installment and real estate loans. Installment and real estate loans Credit Cards and Unsecured Revolving Loans [Member] Represents credit cards and unsecured revolving loans. Credit cards and unsecured revolving loans Unsecured Installment Loans [Member] Represents the unsecured installment loans. Unsecured installment loans Loans Secured With Non Real Estate Collateral [Member] Represents loans secured with non-real estate collateral. Loans secured with non-real estate collateral Non Bank Loans Secured By Real Estate [Member] Represents the non-bank loans secured by real estate. Non-bank loans secured by real estate Non Bank Auto Loans [Member] Represents the non-bank auto loans. Non-bank auto loans Non Bank Unsecured Personal Loans [Member] Represents the non-bank unsecured personal loans. Non-bank unsecured personal loans Unsecured Loans in Bankruptcy [Member] Represents the unsecured loans in bankruptcy. Unsecured loans in bankruptcy Real Estate Secured Loans in Bankruptcy [Member] Represents the real estate-secured loans in bankruptcy. Real estate-secured loans in bankruptcy Non Bank Unsecured Personal Loans In Bankruptcy [Member] Represents the non-bank unsecured personal loans in bankruptcy. Non-bank unsecured personal loans in bankruptcy Loans Charge Off And Interest Accrual Period [Line Items] Loans charge off and interest accrual period Past Due Days for Interest Accrual Ceasing Period for Consumer Loans Represents the period contractually past due for consumer loans after which interest accrual ceases. Past due period for consumer loans when interest accrual ceases (in days) Period For Charging Off Consumer Loans Represents the period contractually past due for consumer loans to be charged off. Period for consumer loans charged-off (in days) Period of Interest or Principal for Corporate Loans Represents the period contractually past due for corporate loans after which loans are considered doubtful. Period for past due interest or principal payment of corporate loans to be considered doubtful (in days) Impaired Financing Receivable with Related Allowance Represents a class of financing receivables that have specific allowances related to the impaired receivables. Impaired loans with valuation allowances Trading Assets and Liabilities [Policy Text Block] Describes an entity's accounting policy for debt and equity securities, derivative instruments, certain loans held in broker-dealer entities, commodities and precious metals. Trading Account Assets and Liabilities Loans Held For Sale [Policy Text Block] Description of how the registrant determines which receivables are initially accounted for as held-for-sale or are later transferred to the held-for-sale classification. Loans Held-for-Sale Reserve Estimates and Policies [Policy Text Block] Describes the policy and method for estimating reserves. Reserve Estimates and Policies Allowance for Unfunded Lending Commitments [Policy Text Block] Describes an entity's accounting policy for allowance for unfunded lending commitments. Allowance for Unfunded Lending Commitments Mortgage Servicing Rights [Policy Text Block] Describes an entity's accounting policy for Mortgage Servicing Rights (MSRs). Mortgage Servicing Rights (MSRs) Representations and Warranties [Policy Text Block] Describes an entity's accounting policy for representations and warranties given at the time of selling a loan. Consumer Mortgage Representations and Warranties Securitizations [Policy Text Block] Describes an entity's accounting policy for securitized credit card receivables and mortgages. Securitizations Cash Flows [Policy Text Block] Describes an entity's accounting policy for cash flows, including risk management activities and capitalized software. Cash Flows Minimum Percentage of Total Expected Variability in Conduits Returns Represents the percentage of total expected variability in the conduit's returns. Minimum percentage of total expected variability in the conduit's returns Securitizations by Balance Sheet Location [Axis] Represents securitizations presented by line items in the statement of financial position. On Balance Sheet Securitizations Represents the amount of on-Balance-Sheet Securitizations. On-Balance-Sheet Securitizations Retained Interests [Axis] This element represents a number of concepts which are required or desirable disclosure items concerning the retained interest. Retained Interests [Domain] Provides eligible items, by category required or determined to be disclosed with respect to the retained interest. Residual Interest [Member] Represents the residual interest in retained interests. Residual interest Represents retained certificates in retained interests. Retained Certificates [Member] Retained certificates Represents other retained interests. Other Retained Interests [Member] Other retained interests Schedule of on Balance Sheet Securitizations Second Segment [Table Text Block] This element represents the schedule of on-Balance-Sheet Securitizations of the second segment. Schedule of On-Balance-Sheet Securitizations Citi Holding Stock Issued During Period, Shares Equity Units Purchase Contract ADIA Upper DECs Equity Units Purchase Contract (in shares) Number of shares issued as result of equity units purchase contract during the period. European Union Capital Accumulation Program Awards [Member] This element represents the Capital Accumulation Program (CAP) for identified staff in the European Union. European Union, CAP awards to identified staff Minimum Number of Future Events for Occurrence of Possible Loss Minimum number of occurrences of future events to be classified as possible loss This element represents the minimum number of occurrence of future events to be classified as possible loss. Subprime Mortgage Litigation [Member] The risk of loss associated with litigation related to the sale of subprime mortgage products by the entity. Subprime Mortgage-Related Litigation and Other Matters Auction Rate Securities Litigation [Member] The risk of loss associated with litigation related to the sale of auction rate securities products by the entity. Auction Rate Securities-Related Litigation and Other Matters Lehman Structured Notes Matters [Member] The risk of loss associated with litigation related to distribution of structured notes by the entity. Lehman Structured Notes Matters Lehman Brothers Bankruptcy [Member] The risk of loss associated with litigation related to transactions with Lehman Brothers prior to their bankruptcy filing. Lehman Brothers Bankruptcy Proceedings Terra Firma Oral Misrepresentation [Member] The risk of loss associated with litigation related to alleged misrepresentations made in connection with the acquisition of EMI. Terra Firma Litigation Knock In Knock Out Derivative Product Losses [Member] The risk of loss associated with litigation related to knock-in, knock-out features of derivative products. KIKOs Tribune Company Bankruptcy [Member] The risk of loss associated with litigation related to the entity's role in the leveraged buyout of Tribune Company. Tribune Company Bankruptcy Interchange Fees Litigation [Member] The risk of loss associated with litigation related to fees associated with Visa and MasterCard-branded payment cards. Interchange Fees Litigation Parmalat Litigation [Member] The risk of loss associated with litigation related to alleged fraud by Parmalat insiders. Parmalat Litigation and Other Matters C I I P Bankruptcy Litigation [Member] The risk of loss associated with an attempt to declare Companhia Industrial de Instruments de Precisao (CIIP) bankrupt. CIIP bankruptcy Allied Irish Bank Litigation [Member] The risk of loss associated with litigation related to fraudulent and fictitious trades entered into by one of the entity's subsidiary's brokers. Allied Irish Bank Litigation Number of Putative Class Actions Against Entity This element represents the number of putative class actions against the entity. Number of putative class actions against entity (in lawsuit) This element represents the common stock closing price per share. Common stock closing price (in dollars per share) Common Stock Closing Price Per Share The number of corporate debt securities, preferred stock, and interests in preferred stock which purchasers allege violated portions of the Securities Act of 1933. Number of corporate debt securities, preferred stock, and interests in preferred stock with alleged violations between 2006 to 2008 Number of Securities Issued on Behalf of which Lead Plaintiffs Assert Claims over Two Year Period The amount of an equity investment in the entity made by a third party. Investments in entity by counterparties and investors' alleged arbitration Third Party Equity Investment The par value of structured debt distributed by the entity. Aggregate par value of structured notes distributed Structured Debt Par Value This element represents the number of current or former employees against whom criminal charges have been brought. Current or former employees Criminal Charges Against Number of Current or Former Employees C K I [Member] This details pertaining to CKI. CKI Loss Contingency Settlement Agreement Consideration Amount Amount of civil penalty which Citigroup agreed to pay This element represents the amount of consideration, which the entity agreed to pay in a settlement agreement which resolved the legal matter. The number of years which the entity agreed to maintain certain disclosure policies, practices and procedures. Period for which Citigroup agreed to maintain disclosure policies, practices and procedures (in years) Number of Years to Maintain Required Disclosures This element represents the fine imposed against subsidiaries in criminal charges. Fine imposed against subsidiary Fine Imposed Against Subsidiaries in Criminal Charges This element represents the maximum value of the confiscation order requested by the criminal court. Maximum confiscation order requested by criminal court Maximum Confiscation Imposed Against Current or Former Employees in Criminal Charges Fine imposed against each individual defendant This element represents the fine imposed against subsidiaries in criminal charges for each individual defendant. Fine Imposed Against Subsidiaries in Criminal Charges for Each Individual Defendant This element represents the number of non-settling civil claims made. Number of non-settling civil claims made Number of Non Settling Civil Claims Made The par value of structured debt distributed by the entity in which settlement was not reached. Aggregate par value of non-settling structured notes Structured Debt Non Settling Claims The amount of setoff that the entity took with respect to clearing obligations, which is the subject of bankruptcy claims. Setoff Citibank N.A. took with respect to certain clearing obligations of LBI Bankruptcy Claim Clearing Obligations Setoff The amount of deposits which LBHI made with the entity prior to its collapse, which is the subject of bankruptcy claims. Deposits made by LBI prior to collapse Bankruptcy Claim Deposits This element represents the custody of proprietary assets and cash held. Proprietary assets and cash of LBIE held in custody Custody of Proprietary Assets and Cash Held The number of plaintiffs in a loss contingency matter. Number of plaintiffs Loss Contingency Number of Plaintiffs Decisions rendered The number of decisions rendered at the district level. Loss Contingency Claims Rendered Number with District Court Number of decision rendered at district court level Number of decisions awarded to plaintiff for portion of damages sought The number of decisions awarded to plaintiff for a portion of the damages sought. Number of Decisions Awarded to Plaintiff for Damages Lender and advisory fees received in connection with LBO The amount of lender and advisory fees received in connection with an LBO which claimants seek to recover. Loss Contingency, Claims Alleged Against Lender and Advisory Fee Received Estimated interchange fees generated by Visa and MasterCard-branded products in the industry This element represents the estimated amount of interchange fees generated by Visa- and MasterCard-branded products during the reporting period by the industry. Interchange Fee Generated U K First Mortgage Portfolio To Held For Sale [Member] Represents the transfer of the U.K. first mortgage portfolio to held-for-sale. U.K. first mortgage portfolio Recognization of Uncertain Tax Position Uncertain tax positions recognized This element represents the tax position that would be booked directly to retained earnings. Unrecognized Tax Benefits, State Income Tax Penalties Accrued State penalties included in total interest and penalties This element represents the amount of statutory penalties accrued under state tax laws as of the date of statement of financial position for a tax position claimed or expected to be claimed by the entity in tax return, which does not meet minimum statutory threshold, to avoid payment of penalties. Expiration Date 2020 [Member] This element represents the expiration date of operating loss carry-forwards and tax credit carry-forwards in 2020. 2020 Number of counterclaims on which favorable verdict was rendered The number of counterclaims on which the entity received a favorable verdict. Loss Contingency, Counterclaims Favorable Verdict, Number Favorable verdict amount, accruing interest The judgment amount of the favorable verdict received on counterclaims. Loss Contingency, Counterclaims Favorable Verdict, Value U S Loans Portfolios To Held For Sale [Member] Represents the sale or transfer of U.S. loan portfolios to held-for-sale. U.S. loan portfolios Outside of North America [Member] Represents loans and lease receivables from entities belonging to a country other than North America. In offices outside North America Commercial Market Loans [Member] Represents the commercial market loan. Commercial market loans Loan to Values [Member] Represents the loan to value ratio, a credit quality indicator. Loan to Values (LTVs) Financing Receivable, Recorded Investment, 30 to 89 Days Past Due Financing receivables that are less than 89 days past due but more than 30 days past due. Loans, 30-89 days past due Financing Receivable, Recorded Investment, 30 to 89 Days Past Due Guaranteed by US Government Sponsored Agencies Financing receivables that are less than 89 days past due but more than 30 days past due and are guaranteed by U.S. government sponsored agencies. Loans, 30-89 days past due, guaranteed by U.S. government-sponsored agencies Financing receivable, credit quality indicator Financing Receivable, Credit Quality Indicator Information [Abstract] Financing Receivable, Credit Quality Scores, Low End of Range Represents the low end of range of the consumer credit score. Consumer credit score, low end of the range Financing Receivable, Credit Quality Scores, High End of Range Represents the high end of range of the consumer credit score. Consumer credit score, high end of the range Financing Receivable, Credit Quality Score [Abstract] Consumer Loans Credit Quality Indicators, FICO score Financing Receivable, Credit Quality Score Less than 620 Financing receivables with credit quality indicator score of less than 620. Loan, credit score less than 620 Financing Receivable Credit Quality, Score 620 or Greater but Less than 660 Financing receivables with credit quality indicator score equal to or greater than 620 but less than 660. Loan, credit score equal to or greater than 620 but less than 660 Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due Guaranteed by US Government Sponsored Agencies Financing receivables that are equal to or greater than 90 days past due and are guaranteed by U.S. government sponsored agencies. Loans, greater than or equal to 90 days past due, guaranteed by U.S. government-sponsored agencies Number of Days Past Due for Considering as Current Represents the number of days past due the loan is less than for consideration as current. Loans 30 or more days past due are not considered current. Loans less than this number of days past due are considered current Financing Receivable, Delinquency Status [Abstract] Delinquency status Number Of Days Past Due For Non Accrual Status Represents the number of days, the loan is past due for classifying as non-accrual. Number of days past due, non-accrual status Financing Receivable, Credit Quality Score Equal to or Greater than 660 Financing receivables with credit quality indicator score of equal to or greater than 660. Loan, credit score equal to or greater than 660 Financing Receivable, Credit Quality Ratio [Abstract] Residential Mortgage Loan to Values Financing Receivable, Credit Quality Ratio Less than or Equal to 80 Percent Financing receivables with credit quality indicator ratio of less than or equal to 80 percent. Loan, credit indicator ratio less than or equal to 80% Financing Receivable, Credit Quality Ratio Greater than 80 Percent but Less than or Equal to 100 Percent Financing receivables with credit quality indicator ratio of greater than 80% but less than or equal to 100 percent. Loan, credit indicator ratio greater than 80% but less than or equal to 100% Financing Receivable, Credit Quality Ratio Greater than 100 Percent Financing receivables with credit quality indicator ratio of greater than 100 percent. Loan, credit indicator ratio greater than 100% Individual Installment and Other [Member] Represents financing receivables classified as installment and other loans from individuals. Individual installment and other Impaired Financing Receivable Recorded Investment without Related Allowance Represents recorded investment of impaired financing receivables without related allowance. Impaired financing receivable without specific allowance Number of Days for Reversal of Interest Accrued on Impaired Loans Charged to Earnings Represents the number of days past due for reversal of accrued interest and to be charged to earnings. Number of days past due for reversal of accrued interest and charging to earnings (in days) Financing Receivable, Recorded Investment, Less than 89 Days Past Due Financing receivables that are equal to 30 - 89 days past due. Loans, equal to 30- 89 days past due and accruing Financing Receivable, Recorded Investment, Past Due and Still Accruing Financing receivables that are past due and still accruing. Loans, total Past due and accruing Impaired Financing, Receivable Recorded, Investment with Related Allowance Represents recorded investment of impaired financing receivables with related allowance. Impaired financing receivable with specific allowance Investment Grade [Member] This element represents the external credit-rating of investment grade. Investment Grade Non Investment Grade [Member] This element represents the external credit-rating of non-investment grade. Non-Investment Grade Percentage of Financing Receivable, Recorded Investment, Current to Total Loans The current financing receivable recorded investment expressed as a percentage of total loans. Percentage of financing receivable, current to total loans Percentage of Financing Receivable, Recorded Investment, Nonaccrual Status to Total Loans The non-accrual financing receivable recorded investment expressed as a percentage of total loans. Percentage of financing receivable, non-accrual status to total loans Percentage of Financing Receivable, Recorded Investment to Total Loans The financing receivable recorded investment expressed as a percentage of total loans. Percentage of financing receivable to total loans Percentage of Private Banking Managed on Delinquency Basis to Loans Percentage of private banking loans managed on a delinquency basis to total loans. Percentage of private banking managed on delinquency to total loans Percentage of Loans Receivable Fair Value Disclosure to Total Loans Percentage of loans receivable at fair value to total loans. Percentage of loans at fair value to total loans Percentage of Loans and Leases Receivable, Net of Deferred Income to Total Loans Percentage of loans and lease receivables, net of deferred income to total loans. Percentage of loans and leases receivable to total loans Schedule of Corporate and Consumer Loans of Consolidated Variable Interest Entities Carried, at Fair Value [Table Text Block] Tabular disclosure of the corporate and consumer loans of consolidated variable interest entities which are carried at fair value. Corporate and consumer loans of consolidated VIEs carried at fair value Tier 1 common capital divided by risk weighted assets, as by Supervisory Capital Assessment Program by U.S. banking regulators. Tier 1 Common ratio (as a percent) Tier One Common Capital Ratio Cash Flows [Abstract] Cash Flows Defined Benefit Plan, Discretionary Cash Contributions by Employer Represents the discretionary cash contribution made by the employer. Discretionary cash contributions by company Highly Leveraged Loans, Carrying Value Highly leveraged loans, carrying value Represents the carrying value of highly leveraged loans reported by the entity as held-for-sale, which are measured on a LOCOM basis. Highly Leveraged Loans, Face Value Highly leveraged loans, face value Represents the face value of highly leveraged loans reported by the entity as held-for-sale, which are measured on a LOCOM basis. Schedule Of Fair Value Of Long Term Debt, Excluding Debt Issued By Consolidated V I Es [Table Text Block] Represents the schedule of fair value of long-term debt, excluding debt issued by consolidated VIEs. Schedule of fair value of long-term debt, excluding debt issued by consolidated VIEs Schedule Of Fair Value Of Short Term Borrowings, Excluding Debt Issued By Consolidated V I Es [Table Text Block] Represents the schedule of fair value of short-term borrowings, excluding debt issued by consolidated VIEs. Schedule of fair value of short term borrowings, excluding debt issued by consolidated VIEs Tier One Common Capital Tier 1 common capital, as defined by Supervisory Capital Assessment Program by U.S. banking regulators. Tier 1 Common Collateralized Personal Loans [Member] Securities collateralized by a pool of personal loans. Personal Loan Securitizations Repurchase and Resale Agreements and Securities Lending and Borrowing Agreements Accounted for as Sales [Policy Text Block] Repurchase and Resale Agreements, and Securities Lending and Borrowing Agreements Accounted for as Sales Disclosure of accounting policy related to repurchase and resale agreements, and securities lending and borrowing agreements accounted for as sales. Residential Mortgage Securitizations Representations and Warranties [Policy Text Block] Securities and Banking-Sponsored Private Label Residential Mortgage Securitizations - Representations and Warranties Disclosure of accounting policy related to representations and warranties of residential mortgage securitizations. Other Assets and Other Liabilities [Policy Text Block] Other Assets and Other Liabilities Disclosure of accounting policy related to other assets and other liabilities. Related Party Transactions [Policy Text Block] Related Party Transactions Disclosure of accounting policy related to transactions with related parties. Incremental Effect of New Accounting Pronouncement on Stockholders' Equity The incremental increase (decrease) in stockholders' equity resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Incremental effect of adopting SFAS 166/167 on stockholders' equity Brokerage Receivables Amount due from customers, brokers, dealers, and clearing organizations related to the entity's brokerage activities and operations. The amount due from customers are for fees and charges arising from transactions related to brokerage activities and operations. The amount receivable from brokers, dealers, and clearing organizations may include receivables for securities borrowed, open transactions, good faith and margin deposits, commissions and floor brokerage items; and would also include cash and securities [guarantee] on deposit with [commodities] clearing organizations and other entities which provide services necessary to operations of the Company. Brokerage receivables Total brokerage receivable Brokerage Payables Amount due to customer, broker-dealers, and clearing organizations related to the entity's brokerage activities and operations. The amount due to broker-dealers and clearing organizations may include amounts payable for securities failed to receive, certain deposits received for securities loaned, amounts payable to clearing organizations on open transactions, and floor-brokerage payables. In addition, the net receivable or payable arising from unsettled trades would be reflected in those captions. A broker-dealer that purchases securities, either for its own account or for a customer's account, but does not receive the securities on the settlement date records the amount of money representing the purchase price of the securities, including any accrued interest, as a liability to the selling broker-dealer. This liability is paid when the securities are received by the purchasing broker-dealer. Brokerage payables Total brokerage payable Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of other short-term borrowing outstanding by type or by instrument at that time. Other Short Term Borrowings Weighted Average Interest Rate Weighted average interest rate of other short-term borrowings (as a percent) Citigroup's Smith Barney Quilter and Australia Private Client Networks Businesses [Member] Represents information pertaining to the reporting entity's Smith Barney, Quilter and Australia private client networks businesses. Citigroup's Smith Barney, Quilter and Australia private client networks businesses Business Disposal Third Party Percentage of Ownership in Disposed Entity after Disposal by Reporting Entity Represents a third party's ownership interest in an entity of which the reporting entity is disposing, after the reporting entity's disposal. Sumitomo Trust's percent of ownership in Nikko Asset Management after disposal by Citigroup All other This category of investments includes corporate debt securities, asset-backed securities, and other debt securities not otherwise defined. Corporate Debt Asset Backed And Other Debt Securities [Member] Goodwill Future Impairment Loss Future material impairment charges This element represents the future material impairment charges due to changes in economic conditions or other events adversely affecting the business models and the related assumptions. Expiration Date 2012 to 2019 [Member] This element represents the expiration date of operating loss carryforwards and tax credit carryforwards between 2012 and 2019. 2012-2019 Undistributed Foreign Profits The amount as of the balance sheet date of undistributed foreign earnings on which the entity has not provided deferred taxes as these amounts are considered to be indefinitely reinvested. Accumulated undistributed profits of non-U.S. subsidiaries considered indefinitely reinvested Held To Maturity Securities Continuous Unrealized Loss Position Twelve Months Or Longer Aggregate Losses For Securities Transferred From Available For Sale This item represents the fair value of securities categorized as held-to-maturity and transferred from available for sale which are in an unrealized loss position. Gross unrecognized losses 12 months or longer for securities reclassified from AFS investments Defined Benefit Plan, Actual Rate of Return on Assets Represents the percentage actual rate of return on asset under defined benefit plan. Actual rate of return (as a percent) Income Taxes Benefit Threshold [Abstract] Income Taxes Income Taxes Benefit Threshold Percentage Minimum percentage likely to be realized for measurement of tax benefit This element represents the minimum percentage likely to be realized threshold for the measurement of tax benefits. Period for Interest Reversal on Impaired Corporate Loans Represents the period contractually past due for corporate loans after which accrued interest is reversed. Time period for reversing accrued interest on impaired corporate loans (in days) Period For Writing Down Secured Consumer Loans Represents the period contractually past due for secured consumer loans after which they are written down to collateral value (less costs to sell). Past due period for secured consumer loans after which they are written down to net collateral value (in days) Sensitivity Analysis of Repurchase Reserve Impact of 10 Percent Adverse Change in Significant Assumptions The hypothetical financial impact of a 10 percent adverse change in significant assumptions on the repurchase reserve. Increase in repurchase reserve due to 10% adverse change in significant assumptions Net Qualified Benefit Plan Expense Represents the amount of net benefit expenses for the qualified plan. Net qualified plans (benefit) expense Nonqualified Benefit Plan Expense Represents the amount of benefit expenses for the nonqualified plan. Nonqualified plans expense In Re Citigroup Inc. Securities Litigation Citigroup, Inc. Securities Litigation [Member] The consolidation of class actions against the entity alleging violations of the Securities Exchange Act of 1934. Institutional Claims [Member] Actions filed by institutional customers on their own behalf. Institutional Claims Asserted Individually Citigroup, Inc. Bond Litigation [Member] The consolidation of class actions against the entity alleging violations of the Securities Act of 1933. In Re Citigroup Inc. Bond Litigation Abu Dhabi Investment Authority [Member] An arbitration action brought by the Abu Dhabi Investment Authority. Arbitration brought by the Abu Dhabi Investment Authority Fine Requested Criminal Charges Fine requested by criminal court This element represents the fine requested for criminal charges brought against a subsidiary. Name of Litigation [Axis] The name of litigation. Litigation [Domain] The listing of specific litigation disclosed by the entity. Regulatory Action By S E C [Member] A regulatory investigation by the SEC. Regulatory action by the SEC Number of Years of Alleged Violations The number of years in which the alleged violations occurred. Number of years of alleged violations (in years) Loss Contingency, Damages Sought Value, Low End of Range The value (monetary amount) which the award the plaintiff seeks in the legal matter exceeds. Collective amount of damages alleged, low end of range Loss Contingency Favorable Decisions The number of favorable decisions for the entity. Decisions favorable to entity Loss Contingency Claims Made The number of claims made as of the balance sheet date. Number of claims made against entity Loss Contingency Damages Awarded The value of damage awards as of the balance sheet date. Total damages awarded Merits Decision Outcome Favorable The decision outcome in a merits proceeding, which was favorable to the entity. Decision in favor of Citi Brazil Allowance for loan losses: Loans and Leases Receivable, Allowance [Abstract] Loans and Leases Receivable Allowance [Axis] Loans and leases receivable allowance account by explanation grouping. Deferred Compensation Arrangements by Plan Type [Table] Disclosures related to deferred compensation plans that are offered to a group of employees that are intended to be paid in cash unless required. Deferred Compensation Arrangements by Plan Type [Line Items] Profit Sharing Plan disclosures Minimum Maturity Period of Investment Included as Contractual Maturities Represents the minimum maturity period for which investments with no stated maturities will be classified as. Minimum contractual maturities of investments with no stated maturities, included as contractual maturities (in years) Defined Contribution Plan Employer Contribution, Matching Percent of Eligible Compensation Next Fiscal Year The percentage of matching contribution made by the employer to a defined contribution plan for participating employees effective next fiscal year. Maximum percentage contribution by employer of employees eligible pay effective next fiscal year Financing Receivable Recorded Investment, Greater than 90 Days Past Due Recorded investment in financing receivables that are greater than 90 days past due. Loans, greater than 90 days past due Installment Loans [Member] Represents financing receivables classified as installment loans. Installment Loans Unsecured Revolving Loans [Member] Represents financing receivables classified as unsecured revolving loans. Unsecured Revolving Loans Expiration Date 2027 [Member] This element represents the expiration date of operating loss carryforwards and tax credit carryforwards in 2027. 2027 Expiration Date 2012 to 2031 [Member] This element represents the expiration date of operating loss carryforwards and tax credit carryforwards between 2012 and 2031. 2012-2031 Financing Receivable without Credit Quality Score Financing receivables where credit quality indicator score was unavailable. Loan without credit score Percentage Of U S Financial Receivable Portfolio Represents the percentage of U.S. loan portfolio. Percentage of U.S. loan portfolio Change in Accumulated Other Comprehensive Income (Loss) Due to Actuarial Assumptions Changes and Plan Experience Represents the amount of change in accumulated other comprehensive income (loss) due to changes in actuarial assumptions and plan experience. Actuarial assumptions changes and plan experience Change in Accumulated Other Comprehensive Income (Loss) Due to Net Asset Gain Represents the amount of change in accumulated other comprehensive income (loss) due to net asset gain as a result of actual returns exceeding expected returns. Net asset gain due to actual returns exceeding expected returns Loss Contingency Disgorgement Represents the amount of disgorgement requested by Milan prosecutors. Amount of disgorgement Loss Contingency Litigation Fine Represents the amount of fine requested by Milan prosecutors. Amount of fine Number of Trust Funded by Reinsurer Number of trusts funded by the reinsurer This element represents the number of trusts funded by the reinsurer. Fair Value of Capitalized Mortgage Servicing Rights Fair value of capitalized mortgage servicing rights Represents the fair value of capitalized mortgage servicing rights. Term Notes Issued to Multiseller Commercial Paper Conduits The par value of liabilities of the credit card receivables securitization trust related to term notes issued to multi-seller commercial paper conduits. Term notes issued to multi-seller commercial paper conduits Allowance For Loan And Lease Losses Replenishment Of Net Charge Offs Reflects the amount of replenishment of net charge-offs for credit losses. Replenishment of net charge-offs Represents the SLM Corporation (Sallie Mae). S L M Corporation [Member] SLM Corporation (Sallie Mae) Disposal Group Including Discontinued Operation Seller Financing This element represents the seller financing provided by an entity to purchaser as a part of sale transaction. Seller-financing Sale of Business Percentage of Ownership Sold Represents the percentage of ownership sold to public investor through IPO. Percentage of ownership sold to public investor through IPO Sale of Business Percentage of Ownership Retained Represents the percentage of ownership retained in business sold. Percentage of ownership retained in business sold Percentage of Reinsurance Represents the percentage of reinsurance of the risk associated with the in-force insurance policies. Percentage of reinsurance Major tax Jurisdictions and the earliest tax year subject to examination Disclosure of components of net deferred tax asset or liability by the applicable tax jurisdiction or component. Major Tax Jurisdictions and Earliest Tax Year Subject to Examination [Table Text Block] This item represents the unrealized loss of fixed income securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. Unrealized Loss Of Fixed Income Securities Neither Classified As Held To Maturity Nor Trading Securities Continuous Loss Position Less Than Twelve Months Unrealized loss of fixed income investments in gross unrealized loss position for less than twelve months Tax on Exchange Offer Booked to Retained Earnings This element represents the tax effect on the change in other adjustments to retained earnings for the period being reported. Tax on exchange offer booked to retained earnings Intangible Assets Excluding Mortgage Servicing Rights Discontinued Operations Represents the decrease in the aggregate amount of intangible assets excluding mortgage servicing rights (MSRs), due discontinued operation during the period. Discontinued Operations Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Amendment Description Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Legal Entity [Axis] Entity [Domain] Number of Significant Accounting Policies Represents the number of significant accounting policies identified by the entity. Number of significant accounting policies Trading Securities, Realized Gain (Loss) Net realized gains included in realized gains (losses) on sales of investments Securities Transferred From Available For sale Securities To Held To Maturity Securities Carrying Value Represents the carrying value of securities transferred from investments available-for-sale to investments held-to-maturity. Debt securities transferred from Investments available-for-sale to Investments held-to-maturity Securities Transferred From Trading Account Assets To Held To Maturity Securities, Carrying Value Represents the carrying value of securities transferred from trading account assets to investments held-to-maturity. Debt securities transferred from trading account assets to investments held-to-maturity Held-to-maturity Securities, Transferred Security, at Carrying Value Investment reclassified from investments held-to-maturity to trading account assets Carrying value of securities reclassified as available-for-sale Held To Maturity Securities Sold Security Realized Gain Loss After Tax Represents the after tax gain (loss) realized on the sale of held-to-maturity securities disposed off during the period. After tax loss recognized in the consolidated statement of income Unrealized Gain (Loss) on Securities Gross unrealized gains included in other revenue Reclassification of Investments by Category [Axis] Information pertaining to reclassification of investment securities by category of investment security. The categories of investment securities are trading, available-for-sale, and held-to-maturity securities. Reclassification of Investments by Category [Domain] Provides the general categories of investment securities consisting of certain investments in debt or equity securities for which reclassification information is given. The categories of marketable securities are trading, available-for-sale, and held-to-maturity securities. Debt Securities Held To Maturity Reclassified Into Trading Account Assets [Member] Represents the reclassification of debt securities from held-to-maturity to trading account assets. Reclassification of debt securities from held-to-maturity to trading account assets Liabilities Held in Trust Total Trust liabilities The par value of liabilities of the credit card receivables securitization trust. Housing Prices Increase Percentage Change Assumptions Future Calendar Year Four and Onwards This element represents the projected percentage increase change in housing prices for the calendar year that is four years after the current fiscal year and onwards, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities. U.S. housing price percentage increase (decrease) change from 2015 onwards Number of Derivative Actions Filed Represents the number of derivative actions filed against various current and former officers and directors of the entity, asserting breach of fiduciary duty arising out of entity's mortgage servicing and foreclosure practices. Number of derivative actions filed Held To Maturity Securities Corporate Loans Sold And Or Reclassified Represents the amount of held-for-investment corporate loans sold and/or reclassified. Held-for-investment corporate loans sold and/or reclassified Floater Inventory Held by Entity Represents the floater inventory related to the customer or proprietary TOB programs that is held by the entity. Floater inventory held by entity Market Value Of Interest In Private Label Re Securitization Entities Related To Current Period Market value of retained interest related to re-securitization transaction in 2012 This element represents the amount of market value of interest owned by the entity in private-label re-securitization entities, for current period. Issuances (redemptions) of preferred stock, net Payments for Repurchase of Preferred Stock and Preference Stock Residential Mortgage Backed Securities Represents the approximate value of amount of securities collateralized by residential real estate mortgage loans. Residential mortgage-backed securities, approximate value Number of Countries Where Entity Provide Broad Range of Banking Services Represents the number of countries where the entity provides a broad range of banking and financial products and services. Number of countries where the entity provides a broad range of banking and financial products and services Represents the sale or transfers to held-for-sale of U.K. Real Estate Lending Loans. U K Real Estate Lending Loans [Member] U.K. real estate lending loans Represents debt securities with senior interest collateralized by real estate mortgage loans (mortgages), issued by non-governmental sponsored enterprises. Mortgage Backed Securities With Senior Interests Issued By Private Enterprises [Member] Senior interests Loan Categories Number Number of loan categories The number of loan categories reported by the entity. Sales Or Reclassification Of Portfolio Loans To Held For Sale Total amount of portfolio loans sold and or reclassified to loans held-for-sale during the period. Sold and/or reclassified consumer loans Represents debt securities with subordinated interest collateralized by real estate mortgage loans (mortgages), issued by non-governmental sponsored enterprises. Mortgage Backed Securities With Subordinated Interests Issued By Private Enterprises [Member] Subordinated interests Represents the amount of original par value of re-securitizations deals in which the entity holds a retained interest. Original par value of re-securitizations deals in which the entity holds a retained interest Original Par Value Of Re Securitizations Deals In Which Entity Holds Retained Interest Original Fair Value Of Re Securitizations Deals In Which Entity Holds Retained Interest Represents the amount of original fair value of re-securitizations deals in which the entity holds a retained interest. Original fair value of re-securitizations deals in which the entity holds a retained interest Assumption for Fair Value of Interests Continued to be Held by Transferor Servicing Assets or Liabilities Weighted Average Expected Credit Losses Represents the rate at which principal will not be repaid on securitized financial assets. This is used as a key input and assumption in measuring the fair value of assets or liabilities that relate to a transferor's continuing involvement (including interests that continue to be held by the transferor and servicing assets or servicing liabilities), if any, as of the date of the latest statement of financial position presented. Weighted average constant prepayment rate, date of sale or securitization (as a percent) The risk of loss associated with litigation related to the Residential Mortgage-Backed Securities investor actions and repurchase claims. Residential Mortgage Backed Securities Investor Actions And Repurchase Claims [Member] Residential Mortgage-Backed Securities Investor Actions and Repurchase Claims Private Label Mortgage Backed Securitization Transactions Sponsored By Entity Represents the amount of private-label mortgage-backed securitization transactions sponsored by Citigroup affiliates. Private-label mortgage-backed securitization transactions sponsored by Citigroup affiliates Loss Contingency, Loss in Period Losses to date on private-label mortgage-backed securitization transactions sponsored by Citigroup affiliates Loss Contingency, Civil Lawsuits Filed Represents the number of civil lawsuits filed by small and medium-sized enterprises. Number civil lawsuits filed by small and medium-sized enterprises Loss Contingency, Decision Prevailed, Number with District Court Represents the number of decision prevailed. Numbers of decision prevailed Loss Contingency, Adverse Decision, Number with District Court Represents the number of adverse decision against which appeal is made by the entity. Number of adverse decision against which appeal is made Represents the consumer loans in the Special Asset Pool (SAP) for which delinquency stats are not available. Consumer Loans in Special Asset Pool [Member] Special Asset Pool (SAP) Income Allocated to Employee Restricted and Deferred Shares that Contain Nonforfeitable Rights to Dividends This element represents the income allocated to employee restricted and deferred shares that contain nonforfeitable rights to dividends. Less: Dividends and undistributed earnings allocated to employee restricted and deferred shares with nonforfeitable rights to dividends, applicable to basic EPS Constant prepayment rate, date of sale or securitization (as a percent) Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities, Prepayment Speed Floor Price Of Asset Backed Commercial Paper Conduits Assets Represents the amount of floor price of asset-backed commercial paper conduits. Floor price of conduit's assets Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Level 3 Carrying (Reported) Amount, Fair Value Disclosure [Member] Carrying value Portion at Fair Value, Fair Value Disclosure [Member] Fair value, fair value option Estimate of Fair Value, Fair Value Disclosure [Member] Fair value Change During Period, Fair Value Disclosure [Member] Changes in fair value gains (losses) Nonrecurring fair value changes included in earnings Categories of Investments, Marketable Securities, Available-for-sale Securities [Member] Investments classified as available-for-sale Fair Value Measurement With Unobservable Inputs Long Term Debt Scheduled Termination Of Structured Transaction Increase (Decrease) In Level Three This element represents the increase (decrease) in the balance of long-term debt related to scheduled termination of a structured transaction at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Increase (decrease) in level 3 of Long-term debt due to scheduled termination of a structured transaction Discount rate, date of sale or securitization (as a percent) Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities, Discount Rate Cash and Cash Equivalents [Member] Cash and short-term investments Internal Revenue Service (IRS) [Member] U.S. Federal Long-term Debt [Member] Long-term debt Short-term Debt [Member] Short-term borrowings Fair Value, Inputs, Level 1 [Member] Level 1 Categories of Investments, Marketable Securities, Held-to-maturity Securities [Member] Investments classified as held-to-maturity Domestic Corporate Debt Securities [Member] U.S. corporate bonds Foreign Corporate Debt Securities [Member] Non-U.S. corporate bond Preferred stock at aggregate liquidation value Preferred Stock [Member] Auction Rate Securities [Member] Auction rate securities Other Debt Obligations [Member] Other debt securities Treasury stock, at cost Treasury Stock [Member] Trust Preferred Securities Subject to Mandatory Redemption [Member] Trust preferred securities. US States and Political Subdivisions Debt Securities [Member] State and municipal securities State and municipal US Treasury and Government [Member] U.S. Treasury and federal agency securities US Treasury Securities [Member] U.S. Treasury U.S. Treasury securities United States Pension Plans of US Entity, Defined Benefit [Member] U.S. Pension Plans United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member] U.S. Postretirement Benefit Plans Variable Annuity [Member] Annuity contracts Variable Interest Entity, Not Primary Beneficiary [Member] Significant unconsolidated VIE assets Consolidated VIEs Variable Interest Entity, Primary Beneficiary [Member] Consolidation, Eliminations [Member] Consolidating adjustments Subsidiaries [Member] Citibank, N.A. and Subsidiaries Swap [Member] Swaps State and Local Jurisdiction [Member] State and Local Subordinated Debt [Member] Subordinated notes Residential Mortgage [Member] Residential First Mortgage Loans Secured Debt [Member] Secured debt Senior Notes [Member] Senior notes Other Postretirement Benefit Plans, Defined Benefit [Member] Postretirement Benefit Plans Pension Plans, Defined Benefit [Member] Pension Plans Performance Guarantee [Member] Performance guarantees Collateralized Mortgage Backed Securities [Member] Mortgage-backed securities Mortgage Loans on Real Estate [Member] Mortgage and real estate Other real estate owned Loans Junior Subordinated Debt [Member] Junior subordinated notes relating to trust preferred securities Liabilities, Total [Member] Total liabilities Line of Credit [Member] Revolving line of credit facility Loans [Member] Loans Investments in Foreign Subsidiaries and Foreign Corporate Joint Ventures that are Essentially Permanent in Duration [Member] Investments in Foreign Subsidiaries and Foreign Corporate Joint Ventures that are Essentially Permanent in Duration Investments [Member] Investments: Interest-bearing Deposits [Member] Interest-bearing deposits Home Equity [Member] Home equity loans Revolving open-end loans secured by one- to four-family residential properties Financial Standby Letter of Credit [Member] Financial standby letters of credit First Mortgage [Member] First mortgages Fixed Income Securities [Member] Debt securities Fixed-income investments Foreign Government Debt Securities [Member] Foreign government Foreign government securities Non-U.S. government bonds Foreign Country [Member] Foreign Foreign Pension Plans, Defined Benefit [Member] Non - U.S. Pension Plans Foreign Postretirement Benefit Plans, Defined Benefit [Member] Non-U.S. Postretirement Benefit Plans Equity Securities [Member] Equity securities Consumer Loan [Member] Consumer Core Deposits [Member] Core deposit intangibles Corporate Debt Securities [Member] Corporate Credit Card Receivable [Member] Credit cards Business Combination [Member] Maltby Acquisitions Limited Cash [Member] Cash Collateralized Mortgage Obligations [Member] Mortgage securitizations Commercial Loan [Member] Corporate loans: Commercial Paper [Member] Commercial paper conduits Commercial Real Estate [Member] Commercial and other real estate Allowance for Loan and Lease Losses [Member] Allowance for loan losses Stock Options [Member] Weighted-average options to purchase common stock Asset-backed Securities [Member] Asset-based financing Asset-backed securities Assets, Total [Member] Total assets Bad Debt Reserve for Tax Purposes of US Savings and Loan Associations or Other Qualified Thrift Lender [Member] Bad Debt Reserve for Tax Purposes of US Savings and Loan Associations or Other Qualified Thrift Lender Loss Contingency Prejudgment Interest Represents the amount of prejudgment interest pursuant to the proposed settlement. Amount of prejudgment interest Equity Investments by Investment Authority Represents the amount of investment in Citigroup by Abu Dhabi Investment Authority (ADIA). Investment in Citigroup by Abu Dhabi Investment Authority (ADIA) Loss Contingency, New Claims Filed, Number Lawsuits against Citigroup, number Financing Receivables Principal Forgiven Represents the amount of financing receivables' principal forgiven by the holder of the instrument. Principal forgiveness Balance of principal forgiven or deferred Financing Receivables Troubled Debt Restructuring Loans in Default Represents the amount of troubled debt restructuring loans that defaulted during the current year and for which the payment default occurred within one year of the modification. Loans in default TDR Loans in payment default Financing Receivables Troubled Debt, Restructuring Involving Change in Amount or Timing of Principal Payment Represents the amount of troubled debt restructurings involving changes in the amount or timing of principal payments. TDRs involving changes in the amount and/or timing of principal payments Financing Receivables Troubled Debt, Restructuring Involving Change in Amount or Timing of Interest Payment Represents the amount of troubled debt restructurings involving changes in the amount or timing of interest payments. TDRs involving changes in the amount and/or timing of interest payments Financing Receivables Troubled Debt, Restructuring Involving Change in Amount or Timing of Principal Interest Payment Represents the amount of troubled debt restructurings involving changes in the amount or timing of principal and interest payments. TDRs involving changes in the amount and/or timing of both principal and interest payments Financing Receivables Troubled Debt, Restructuring Impact on Net Profit and Loss Represents the amount of troubled debt restructurings on net profit and loss. Net P&L Impact Financing Receivable Troubled Debt Restructurings that Subsequently Defaulted [Table Text Block] Tabular disclosure of troubled debt restructuring (TDR) loans that defaulted during the period and for which the payment default occurred within one year of the modification. Schedule of troubled debt restructuring loans that defaulted Represents the increase (decrease) in the balance of investments, due to sales and redemptions of investments in private equity and hedge funds. Fair Value Measurement with Unobservable Inputs Investments Increase (Decrease) in Level Three Due to Sales and Redemptions of Private Equity and Hedge Fund Increase (decrease) in investments due to sales and redemptions of investments in private equity and hedge funds Fair Value Measurement with Unobservable Inputs Investments Increase (Decrease) in Level Three Due to Purchase of Private Equity and Hedge Funds Increase (decrease) in investments due to purchase of investments in private equity and hedge funds Represents the increase (decrease) in the balance of investments, due to the purchase of investments in private equity and hedge funds. Financing Receivables Troubled Debt Restructuring, Carrying Value Carrying Value Represents the carrying value of loans receivable modified in a troubled debt restructuring during the current year. Financing Receivables Troubled Debt, Restructuring Loans Modified Carrying Value Represents the carrying value of loans receivable modified in a troubled debt restructuring during the current year. Carrying Value Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Gain (Loss) Due to Credit Spreads Widening included in Principal Transactions Losses on bespoke CDO and index CDO positions due to credit spreads widening Represents total gains or losses during the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3) due to credit spreads widening, which are included in earnings or resulted in a change in the net asset value and are included in the income statement in principal transactions. Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Gain (Loss) Recorded on Total Return Swaps Referencing Returns on Corporate Loans Loss recorded on total return swaps referencing returns on corporate loans Represents total gains or losses during the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3), recorded on total return swaps referencing returns on corporate loans which are included in earnings or resulted in a change in the net asset value. PLEDGED ASSETS, COLLATERAL, COMMITMENTS AND GUARANTEES Transfer of Loans Held-for-sale to Portfolio Loans Transfers to loans held for investment (loans) from loans held-for-sale Other Noncash Income (Expense) Other, net Total Citigroup common stockholders' equity and common shares outstanding Common Stockholders' Equity Other (in shares) Stockholders' Equity, Other Shares Origination of a noncontrolling interest Variable Interest Entity, Initial Consolidation, Gain (Loss) Long-term debt, at fair value Long-term debt, at fair value Long-term Debt, Fair Value Long-term debt ALLOWANCE FOR CREDIT LOSSES Allowance for Credit Losses [Text Block] GOODWILL AND INTANGIBLE ASSETS DEBT Scenario, Previously Reported [Member] Previously Reported Increase (Decrease) from Transactions Between Noncontrolling Interest Shareholders and Related Consolidating Subsidiary Transactions between noncontrolling-interest shareholders and the related consolidated subsidiary Increase (decrease) in noncontrolling interest related to transactions with consolidating subsidiary. Common Stock, Dividends, Per Share, Declared Common dividends declared (in dollars per share) DISCONTINUED OPERATIONS INCENTIVE PLANS RETIREMENT BENEFITS INCOME TAXES EARNINGS PER SHARE BROKERAGE RECEIVABLES AND BROKERAGE PAYABLES CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) DERIVATIVES ACTIVITIES CONCENTRATIONS OF CREDIT RISK CONTINGENCIES Subsequent Events [Text Block] SUBSEQUENT EVENT SUBSEQUENT EVENT SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) CONDENSED CONSOLIDATING FINANCIAL STATEMENTS SCHEDULES BUSINESS SEGMENTS Description of assets pledged, collateral received by the Company, lease commitments, guarantee obligations and credit commitments. Pledged Assets Collateral Commitments and Guarantees [Text Block] GUARANTEES AND COMMITMENTS CONDENSED CONSOLIDATING FINANCIAL STATEMENTS SCHEDULES Condensed Consolidating Financial Statements Disclosure [Text Block] The entire disclosure of the condensed financial statements (balance sheet, income statement and statement of cash flows), normally using the registrant (parent) as the sole domain member. If condensed consolidating financial statements are being presented, other domain members (in addition to parent) such as guarantor subsidiaries, non-guarantor subsidiaries, and the consolidation eliminations, will be included in order that the respective monetary amounts for each of the domains will aggregate to the respective amounts on the consolidated financial statements. Other-than-temporary impairment losses on investments Other than Temporary Impairment Losses, Investments [Abstract] Less: Impairments recognized in AOCI Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), before Tax, Including Portion Attributable to Noncontrolling Interest Net impairment losses recognized in earnings Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities Net impairment losses recognized in earnings Federal funds purchased and securities loaned or sold under agreements to repurchase, at fair value Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure Federal funds purchased and securities loaned or sold under agreements to repurchase Short-term borrowings, at fair value Short-term Debt, Fair Value Short-term borrowings Other liabilities, at fair value Other Liabilities, Fair Value Disclosure Nontrading derivatives and other financial liabilities measured on a recurring basis, gross Other financial liabilities Stock tendered for payment of withholding taxes Payments Related to Tax Withholding for Share-based Compensation Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents, Continuing Operations Balance (in shares), beginning of year Balance (in shares), end of year Shares, Issued Shares outstanding Preferred stock Series H discount accretion Preferred Stock, Accretion of Redemption Discount Payment and Performance Risk (Credit Rating) [Axis] Derivative Instrument Risk [Axis] Fair Value, Hierarchy [Axis] Adjustments for Change in Accounting Principle [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Investment Type Categorization [Domain] Segment [Domain] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Gross unrealized losses of available for sale securities that have been in an unrealized loss position for twelve months or longer Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses Total gross unrealized losses of available for sale securities that have been in an unrealized loss position Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses Gross unrealized losses of available for sale securities that have been in an unrealized loss position for less than twelve months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses Available-for-sale Securities, Debt Securities Total fair value Cash Flows Between Transferor and Transferee, Servicing Fee Advances Cash flows received on retained interests and other net cash flows Cash Flows Between Transferor and Transferee, Proceeds from Collections Reinvested in Revolving Period Transfers Proceeds from collections reinvested in new receivables Cash Flows Between Transferor and Transferee, Proceeds from New Transfers Proceeds from new securitizations Cash Flows Between Transferor and Transferee, Servicing Fees Contractual servicing fees received Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercised (in options) Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Maximum exposure to loss in significant unconsolidated VIEs Maximum exposure Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Allowance for Credit Losses on Financing Receivables [Table Text Block] Schedule of allowance for credit losses and investment in loans by portfolio segment Impaired Financing Receivables [Table Text Block] Schedule of impaired consumer loans Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), before Tax, Including Portion Attributable to Noncontrolling Interest, Held-to-maturity Securities Net unrealized losses recorded in AOCI and excluded from gross unrecognized losses Schedule of Assumptions Used [Table Text Block] Assumptions used in determining pension and postretirement benefit obligations and net benefit expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of components of income tax expense (benefit) Schedule of Credit Losses Related to Financing Receivables, Current and Noncurrent [Table Text Block] Allowance for credit losses Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Deferred income taxes Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Reconciliation of the federal statutory income tax rate to the Company's effective income tax rate applicable to income from continuing operations (before noncontrolling interests and the cumulative effect of accounting changes) Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block] Effect of one-percentage-point change in assumed health-care cost- trend rates Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block] Reconciliations of the beginning and ending balances during the period for Level 3 assets Schedule of Expected Benefit Payments [Table Text Block] Estimated Future Benefit Payments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Future minimum annual rentals under noncancelable leases, net of sublease income Schedule of Health Care Cost Trend Rates [Table Text Block] Assumed health-care cost-trend rates, U.S plans Schedule of Impaired Financing Receivable [Table] Schedule of Maturities of Long-term Debt [Table Text Block] Aggregate annual maturities of long-term debt obligations Schedule of Net Benefit Costs [Table Text Block] Retirement benefits, components of net (benefit) expense Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of amounts recognized in Other Revenue in the Consolidated Statement of Income related to derivatives not designated in a qualifying hedging relationship and underlying non-derivative instruments Schedule of Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table] Schedule of Quarterly Financial Information [Table Text Block] SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) Troubled Debt Restructurings on Financing Receivables [Table Text Block] Schedule of troubled debt restructurings Financing Receivable Information by Credit Quality Indicator [Axis] Financing Receivable Information by Portfolio Segment [Axis] Investments, Debt and Equity Securities [Abstract] Investments summary Variable Interest Entity, Consolidated, Carrying Amount, Assets Consolidated VIE / SPE assets Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Total Consolidated Liabilities Loans receivable Financing Receivable, Recorded Investment [Line Items] Financing Receivable, Recorded Investment, Nonaccrual Status Loans, total non-accrual Impaired Financing Receivable, Average Recorded Investment Average Carrying Value Average carrying value Impaired Financing Receivable, Interest Income, Accrual Method Interest Income Recognized Interest income recognized Recorded investment in loans modified under the ASU Recorded investment Impaired Financing Receivable Recorded Investment Impaired Financing Receivable, Related Allowance Related specific allowance Allowance for credit losses associated with loans modified under the ASU Financing receivable impaired Financing Receivable, Impaired [Line Items] Financing Receivable, Individually Evaluated for Impairment Loans individually evaluated for impairment in accordance with ASC 310-10-35 Impaired Financing Receivable, Unpaid Principal Balance Principal balance Unpaid principal balance Letters of Credit Outstanding, Amount Outstanding letters of credit Loss Contingency, Damages Sought, Value Alleged loss by counterparties and investors on investments in entity New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification Impact of the adoption of ASU Operating Leases, Rent Expense, Net Rental expense Other investments Other Investments [Member] Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, Additional Credit Losses Credit impairments recognized in earnings on securities that have been previously impaired Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, No Previous Impairment Credit impairments recognized in earnings on securities not previously impaired Other than Temporary Impairment, Credit Losses Recognized in Earnings, Categories of Investments [Domain] Goodwill, Translation Adjustments Foreign exchange translation Financing Receivable, Modifications, Recorded Investment Amounts of such outstanding modified consumer loans, including those modified prior to 2008 Deferred principal Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing Loans, 90 days past due and accruing Loans, greater than or equal to 90 days past due and accruing Financing Receivable, Recorded Investment, Current Recorded investment in loans Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due Loans, greater than or equal to 90 days past due Financing Receivable, by Credit Quality Indicator [Domain] Financing Receivable, Collectively Evaluated for Impairment Loans collectively evaluated for impairment in accordance with ASC 450-20 Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality Determined in accordance with ASC 310-30 Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Determined in accordance with ASC 450-20 Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment Determined in accordance with ASC 310-10-35 Loan loss reserve Financing Receivable, Allowance for Credit Losses [Line Items] Accumulated Other Comprehensive Income (Loss), Other than Temporary Impairment, Not Credit Loss, Net of Tax, Held-to-maturity, Debt Securities After tax unrealized losses reflected in AOCI Consumer Credit Scores (FICOs) Consumer Credit Score [Member] Debt Instrument, Basis Spread on Variable Rate Coupon rate, basis spread (as a percent) Debt Instrument, Description of Variable Rate Basis Description of coupon rate basis Reference rate Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year Additional contribution expected to be made by the company in 2012 Financing Receivable, Acquired with Deteriorated Credit Quality Loans acquired with deteriorated credit quality in accordance with ASC 310-30 Financing Receivable Allowance [Domain] Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held Balance at beginning of period Balance at end of period Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward] Schedule of other-than-temporary impairment, credit losses recognized in earnings, roll forward Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities Gross unrealized losses included in other-than-temporary-impairment losses on investments Real estate funds Real Estate Funds [Member] BASIS OF PRESENTATION Common Stock, Par or Stated Value Per Share [Abstract] Common stock price per share Common Stock, Price Per Share High End of Range Represents the maximum price per share of the common stock. High (in dollars per share) Common Stock, Price Per Share Low End of Range Represents the minimum price per share of the common stock. Low (in dollars per share) Common Stock, Closing Value Per Share Represents the closing price per share of the common stock. Close (in dollars per share) Revenue Correction of Error, Net of Tax After-tax impact on revenue due to correction of a CVA error Represents the amount of impact, net of tax, on revenue due to correction of a CVA error in prior periods. Adjustments for Change in Accounting Principle [Domain] Long-term Debt, Weighted Average Interest Rate Overall weighted average interest rate for long-term debt (as a percent) Consolidation, Variable Interest Entity, Policy [Policy Text Block] Variable Interest Entities Securities Borrowed and Loaned Policy [Policy Text Block] Securities Borrowed and Securities Loaned Repurchase and Resale Agreements Policy [Policy Text Block] Repurchase and Resale Agreements Intangible Assets, Finite-Lived, Policy [Policy Text Block] Intangible Assets Pension and Other Postretirement Plans, Policy [Policy Text Block] Employee Benefits Expense Schedule of Principal Transactions Revenue [Table Text Block] Principal transactions revenue Realized Gain (Loss) on Investments [Table Text Block] Realized gains and losses on investments Schedule of Financing Receivables, Non Accrual Status [Table Text Block] Schedule of loan delinquency and non-accrual details Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Derivative Notionals Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block] Change in accumulated other comprehensive income (loss) from cash flow hedges Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Items measured at fair value on a recurring basis Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Changes in each component of Accumulated Other Comprehensive Income (Loss) Recurring Fair Value, Measurements, Recurring [Member] Fair Value by Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets and Liabilities Measured at Fair Value on a Recurring Basis Items Measured at Fair Value on a Nonrecurring Basis Trading Securities, Fair Value Disclosure Trading securities Trading account assets Derivative Asset Cash Collateral Fair Value Disclosure Represents the fair value of cash collateral paid related to derivatives assets. Gross cash collateral paid Mortgage servicing rights (MSRs) Mortgage Servicing Rights Fair Value Disclosure Represents the fair value of mortgage servicing rights (MSRs). Assets, Fair Value Disclosure Total assets Fair value of assets as of the balance sheet date Total assets Gross cash collateral received Derivative Liability Cash Collateral Fair Value Disclosure Represents the fair value of cash collateral paid related to derivatives liabilities. Liabilities, Fair Value Disclosure Total liabilities Fair value of liabilities as of the balance sheet date Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair value, assets and liabilities measured on recurring basis, level 3 fair-value category disclosures Fair Value, Measurements, Nonrecurring [Member] Nonrecurring Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Purchases, assets Purchases of securities Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis,Asset, Issues Issuance, assets Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Sales, assets Sales of securities Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Net settlements Settlements, assets Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Purchases, liability Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issues Issuance, liability Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales Sales, liability Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Settlements, liability Hedging Designation [Axis] Hedging Designation [Domain] Derivative instruments designated as ASC 815 (SFAS 133) hedges Designated as Hedging Instrument [Member] Hedging instruments under ASC 815 (SFAS 133) Securities Sold, Not yet Purchased, Fair Value Disclosure Securities sold, not yet purchased Concentration Risk by Benchmark [Axis] Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities Total Liabilities Schedule of Allocation of Plan Assets [Table Text Block] Asset allocations and target allocations for 2012 by asset category based on asset fair values Range [Axis] Range [Domain] Maximum [Member] Maximum High end of range Minimum [Member] Minimum Low end of range Cumulative Other-Than-Temporary Impairment Credit Losses Recognized in Earnings Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table Text Block] After-tax impact on net income due to correction of a CVA error Cumulative Effect on Retained Earnings, Net of Tax Gross unrealized losses recognized in AOCI Gross unrealized losses Available-for-sale Securities, Gross Unrealized Losses Gross unrealized gains recognized in AOCI Gross unrealized gains Available-for-sale Securities, Gross Unrealized Gains This element represents the minimum number of payments on a modified loan to return to interest accrual status. Minimum number of payments on a modified loan to return to accrual status Minimum Number of Payments for Interest Accrual on Modified Loans Schedule of other than temporary impairment, credit losses recognized in earnings, disclosures Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] Information by Category of Debt Security [Axis] Unemployment Rate Assumptions, Next Calendar Year Unemployment rate for 2012 (as a percent) This element represents the projected unemployment rate for the next calendar year. Accounting Standard Update on Troubled Debt Restructurings [Member] The impact from a change in accounting for Troubled Debt Restructurings due to ASU No. 2011-02, Creditor's Determination of whether a Restructuring is a Troubled Debt Restructuring. Troubled Debt Restructurings (TDRs) Loans Modified under Accounting Standard Update Represents the amount of loans modified under the Accounting Standard Update (ASU). Loans modified under the ASU Allowance for Credit Losses Associated with Loans Modified under, Accounting Standard Update Represents the amount of allowance for credit losses associated with loans modified under the Accounting Standard Update (ASU). Allowance for credit losses associated with loans modified under the ASU Reserves Released for Implementing Prohibition on Valuation Adjustments Represents the amount of reserves released as a result of implementing the prohibition on valuation adjustments. Reserves released as a result of implementing the prohibition on valuation adjustments Incentive Pay Required to be Deferred before Rise Percentage Represents the percentage of incentive pay required to be deferred before rise. Percentage of incentive pay required to be deferred before rise Incentive Pay Required to be Deferred Percentage Represents the percentage of incentive pay required to be deferred. Percentage of incentive pay required to be deferred Deferred Portion Delivered as Deferred Cash Award Percentage Represents the percentage of deferred portion delivered as a deferred cash award. Percentage of deferred portion delivered as a deferred cash award Notional Interest on Deferred Cash Award Annual Rate Represents the annual rate of notional interest on deferred cash award which is compounded annually. Annual rate of notional interest on deferred cash award Vesting period, minimum (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Minimum Vesting period, maximum (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Maximum Global Consumer Banking [Member] Global Consumer Banking This element represents the Global Consumer Banking business segment. Other Incentive Compensation [Member] Represents the other incentive compensation which includes deferred cash awards given to new hires in replacement of prior employer's awards or other forfeited compensation. Other Incentive Compensation Financing Receivable Modifications Number of Payments Represents the minimum number of payments required under consumer loans to qualify these loans for modifications. Minimum number of payments required for modification of loans Financing Receivable Recorded Investment Past Due Guaranteed By U S Government Sponsored Agencies Loans, Past due Government guaranteed Recorded investment in financing receivables that are past due at the balance sheet date and are guaranteed by U.S. government sponsored agencies. Cumulative Effect of Adoption of New Accounting Standards Recognition of Deferred Tax Assets Cumulative effect of initial adoption of new accounting standard on retained earnings which resulted into recognition of deferred tax assets. Deferred tax asset recorded Commingled Funds [Member] Represents the fund consisting of assets from several accounts that are blended together. Commingled funds Financing Receivable Re Age Modifications Limitations In Twelve Months Represents the number of re-age modification limitations in twelve months. Number of re-age modification limitations in twelve months Financing Receivable Re Age Modification Limitations In Five Years Represents the number of re-age modification limitations in five years. Number of re-age modification limitations in five years Open Ended Consumer Loans [Member] Open-ended consumer loans Represents the open-ended consumer loans. Accounting Standard Update on Impairment of Loan [Member] The impact from a change in accounting for impairment of loan due to adoption of ASU No. 2011-02. Impairment of loan Cash Basis Loans Period of Repayment Performance Represents the period of repayment performance for cash-basis loans to return to an accrual status. Cash-basis loans, period of repayment performance (in months) Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block] Allowance for Loan Losses PRINCIPAL TRANSACTIONS Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Financing Receivable Credit Quality Indicators [Table Text Block] Schedule of loans credit quality indicators Foreign Currency Exchange Rate, Translation Exchange rate used at disposal date (in yen to US dollar) Accumulated Defined Benefit Plans Adjustment [Member] Pension liability adjustments Available-for-sale Securities [Abstract] Securities available-for-sale Held To Maturity Securities Unrecognized Holding Loss Gross unrecognized gains Held-to-maturity Securities Unrecognized Holding Loss Gross unrecognized losses Financing Receivable, Recorded Investment, by Class of Financing Receivable [Axis] Financing Receivable, Recorded Investment, Class of Financing Receivable [Domain] Administration and other fiduciary fees Revenue, Other Financial Services Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Issuance of shares pursuant to employee benefit plans Citi Belgium [Member] Citi Belgium business Represents the business of Citi Belgium transferred to held for sale. Finance, Loans and Leases Receivable, Policy [Policy Text Block] Loans Derivatives, Policy [Policy Text Block] Risk Management Activities-Derivatives Used for Hedging Purposes Schedule of Disposal Groups Including Discontinued Operations Egg Banking [Table Text Block] The summarized financial disclosure for discontinued operations, including cash flows, for the credit card operations related to Egg Banking PLC. Summarized financial information for the credit card operations related to Egg Banking PLC. Schedule of Distressed Loan Purchased [Table Text Block] Disclosure of carrying amount of the purchased distressed loan portfolio as of fiscal year. Schedule of changes in the accretable yield, related allowance and carrying amount, net of accretable yield REGULATORY CAPITAL Regulatory Capital Requirements under Banking Regulations [Text Block] REGULATORY CAPITAL Allowance for Loan and Lease Losses, Provision for Loss, Net [Abstract] Provisions for credit losses and for benefits and claims INVESTMENTS Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] INVESTMENTS LOANS FAIR VALUE OF FINANCIAL INSTRUMENTS FAIR VALUE MEASUREMENT Financial Instruments Disclosure [Text Block] FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value Disclosures [Text Block] FAIR VALUE MEASUREMENT Research Analyst Litigation [Member] Represents the putative research-related customer class action alleging various state law claims arising out of the issuance of allegedly misleading research analyst reports concerning numerous issuers. Research Analyst Litigation Citigroup Global Markets Inc [Member] Represents the Citigroup's U.S. broker-dealer Citigroup Global Markets Inc. (CGMI). Citigroup Global Markets Inc. (CGMI) Mortgage Backed Securities Trusts, Percentage of Voting Rights Represents the minimum percentage of voting rights held by Gibbs & Bruns LLP's clients in MBS trusts issued and/or underwritten by Citigroup affiliates. Minimum percentage of voting rights held in MBS trusts Mortgage Backed Securities Trusts, Aggregate Outstanding Balance Represents the minimum aggregate outstanding balance in mortgage-backed securities trusts. Minimum aggregate outstanding balance in MBS trusts Mortgage Backed Securities Trusts, Requisite Interest Held, Number Represents the number of MBS trusts in which requisite interests were held by Gibbs & Bruns LLP clients. Number of MBS trusts in which requisite interests were held by Gibbs & Bruns LLP clients Mortgage Backed Securities, Trusts Total Unpaid Principal Balance Represents the amount of total unpaid principal balance in MBS trusts in which requisite interests were held by Gibbs & Bruns LLP clients. Total unpaid principal balance in MBS trusts in which requisite interests were held by Gibbs & Bruns LLP clients Number of ASTAMAT Investors Represents the number of ASTA/MAT investors. Number of ASTA/MAT investors Additional Deposits Represents the amount of additional deposits currently held by Citibank and its affiliates. Additional deposits Proprietary Assets and Cash of Bankrupt Entity Represents the amount of proprietary assets and cash of bankrupt entity which is held by Citigroup as a custodian. Proprietary assets and cash of LBIE Period of Leave Granted to Putative Representative Plaintiff by Court to File Amended Complaint Represents the period of leave granted to the putative representative plaintiff by the court to file an amended complaint. Period of leave granted by court to file an amended complaint (in days) Change in accumulated other comprehensive income (loss) Increase (Decrease) in Accumulated Other Comprehensive Loss (Income) Net of Tax [Roll Forward] Bankcard and Private Label Merchant Processing Services, Maximum Potential Contingent Liability Represents the entity's maximum potential contingent liability related to both bankcard and private-label merchant processing services, which is estimated to be the total volume of credit card transactions that meet the requirements to be valid chargeback transactions at any given time. Maximum potential contingent liability related to bankcard and private-label merchant processing services Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Reconciliation of the income and share data used in the basic and diluted earnings per share computations Principal transactions revenue Principal Transaction Revenue [Line Items] Realized and unrealized gains and losses from derivative and non-derivative trading activities Number of Saudi Nationals and Related Entities Represents the number of Saudi nationals and related entities. Number of Saudi nationals and related entities (in Plaintiff) Losses Resulting from Options Trades Referencing Portfolio of Hedge Funds Represents the amount of losses resulting from certain options trades referencing a portfolio of hedge funds. Losses resulting from certain options trades referencing a portfolio of hedge funds Principal Transaction Revenue [Table] Maximum Period in Foreclosure Process for Writing Down Represents the maximum period in the foreclosure process after which loans are written down to net collateral value. Maximum period in foreclosure process to write down loans to net collateral values (in months) Past Due Period for Commencing Foreclosure Process Represents the period contractually past due after which the foreclosure process must commence. Past due period of contractual payments after which the foreclosure process should be started (in days) Maximum Past Due Period for Writing Down Secured Loans Represents the maximum number of days past due of contractual payments to write down secured loans to net collateral values as per entities' policy. Maximum past due period of contractual payments to write down secured loans to net collateral values (in days) Past Due Period For Charging Off Represents the period contractually past due for consumer loans to be charged off if there have been no payments within the last six months. Past due period of contractual payments to charge-off if no payments in six months (in days) Maximum Past Due Period Represents the maximum number of days past due of contractual payments for loans in the entity's portfolio. Maximum past due period of contractual payments (in days) Maximum Notification Period for Charging Off Loans Represents the maximum period from receiving bankruptcy court filing notification to charge-off loans. Maximum period from receiving bankruptcy court filing notification to charge-off (in days) Maximum Notification Period for Writing Down Secured Loans Represents the maximum period from receiving bankruptcy court filing notification to write down secured loans to net collateral values. Maximum period from receiving bankruptcy court filing notification to write down secured loans (in days) Equity Method Investment, Ownership Percentage, Low End This element represents the low end of range of percentage of ownership of common stock or equity participation in the investee in which the investee is accounted for under the equity method of accounting. Equity method investment ownership, low end of range (as a percent) Equity Method Investment, Ownership Percentage, High End This element represents the high end of range of percentage of ownership of common stock or equity participation in the investee in which the investee is accounted for under the equity method of accounting. Equity method investment ownership, high end of range (as a percent) Sale of Business, Percentage of Ownership Sold to Private Equity Firm Represents the percentage of ownership sold to private equity firm. Percentage of ownership sold to private equity firm Percentage Of Ownership Contributed To Stock Based Awards Represents the percentage of ownership contributed for employees and agent stock-based awards. Percentage of ownership contributed for employees and agent stock-based awards Citigroup Sold Its Canadian Master Card Business And U S Retail Sales Finance Portfolio [Member] Represents information pertaining to the reporting entity's Canadian MasterCard business and U.S. retail sales finance portfolio. Citigroup's Canadian MasterCard business and U.S. retail sales finance portfolio Portion Assets of Disposal Group Including Discontinued Operation Sold The amount of assets sold in the transaction. Portion amount of assets sold Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate Effect of tax law changes Derivative Cash Collateral Paid The gross amount of cash collateral paid with respect to derivative instruments, before consideration of any master netting arrangements. Cash collateral paid, gross Derivative Cash Collateral Received The gross amount of cash collateral received with respect to derivative instruments, before consideration of any master netting arrangements. Cash collateral received, gross Settlement of Litigation [Member] Agreement in Principle with Certain U.S. Federal Government Agencies and State Attorneys General Effect on Earnings after Tax Due to Settlement Residential Loan Related Investigations with Government Represents effect on earnings after tax which is retro back to reporting date due to additional charge to settle with U.S. Federal government agencies and state attorneys a number of related investigations into residential loan servicing and origination practices. Effect on reporting operating results due to additional charge relating to the agreement with government, after tax Investment Securities Pledged as Collateral at Carrying Value Represents the carrying value, as of the date of each statement of financial position presented, of investment securities which are owned but pledged. Investment securities Loans Pledged as Collateral at Carrying Value Represents the carrying value, as of the date of each statement of financial position presented, of loans which are owned but pledged. Loans Trading Account Assets Pledged as Collateral at Carrying Value Represents the carrying value, as of the date of each statement of financial position presented, of trading account assets which are owned but pledged. Trading account assets Vested shares sale restriction period (in months) Assets Pledged as Collateral at Carrying Value Represents the carrying value, as of the date of each statement of financial position presented, of assets which are owned but pledged. Total Assets Pledged as Collateral at Carrying Value [Abstract] Carrying values of the significant components of pledged assets recognized Servicing Asset at Fair Value, Disposals Sale of MSRs Weighted Average F I C O Scores Of Collateral Weighted average FICO score of the underlying collateral for Alt-A mortgage securities recorded at fair value Weighted average FICO scores of underlying collateral of Alt-A non-agency residential mortgage-backed securities. Fair Value Measurement Pretax Gain Recognized Due to Change in Fair Value Measurement Input Represents the pre-tax gain recognized due to change in fair value measurement input. Pre-tax gain recognized due to change in fair value measurement input Non Trading Derivatives and Other Financial Assets Fair Value Disclosure Represents the fair value of nontrading derivatives and other financial assets of the entity. Nontrading derivatives and other financial assets measured on a recurring basis, gross Other Financial Assets Cash Collateral Fair Value Disclosure Represents the fair value of cash collateral paid related to other financial assets. Gross cash collateral paid Other Financial Liabilities Counterparty Netting and Market Value Adjustment Represents the sum of the amount of netting of other financial liabilities exposures covered by a qualifying master netting agreement and market adjustments (if any) related to derivative liabilities. Netting agreements and market value adjustments Other Financial Assets Counterparty Netting and Market Value Adjustment Represents the sum of the amount of netting of other financial assets exposures covered by a qualifying master netting agreement and market adjustments (if any) related to derivative assets. Netting agreements and market value adjustments Other Financial Liabilities Cash Collateral Fair Value Disclosure Represents the fair value of cash collateral received related to other financial liabilities. Gross cash collateral received Non Trading Derivatives Liabilities Fair Value Disclosure Represents the fair value of nontrading derivatives of the entity. Nontrading derivatives and other financial liabilities measured on a recurring basis Hedge Funds Receivables [Member] Hedge fund receivables Represents the information related to hedge fund receivables. Defined Benefit Plan Other Investment Liabilities Other investment liabilities Represents the aggregate fair value amount, as of the balance sheet date, of other investment liabilities. Defined Benefit Plan Fair Value of Plan Assets, Net Total net assets Represents the net of assets and liabilities. Debt Securities, Transferred to Trading Account Assets or Sold [Table Text Block] Tabular disclosure of debt securities transferred to trading account assets or sold. Carrying value and fair value of debt securities transferred to Trading account assets or sold Transfers From Held To Maturity Investments To Trading Account Assets Subsequently Sold Investment reclassified from investments held-to-maturity to trading account assets subsequently sold substantially Value of investments transferred to trading account assets from held-to-maturity category in noncash transactions which were subsequently sold substantially. Settlement (gain) loss Defined Benefit Plan, Recognized Net (Gain) Loss Due to Settlements Alternative Investment Funds Redemption Notice Period, Maximum Alternative investment funds, maximum redemption notice period (in days) Represents the maximum redemption notice period of alternative investment funds. Alternative Investment Funds Redemption Notice Period, Minimum Alternative investment funds, minimum redemption notice period (in days) Represents the minimum redemption notice period of alternative investment funds. Prepayment Rate, Maximum Prepayment rate, Maximum This element represents the maximum projected prepayment rate CRR which is the annualized expected rate of voluntary prepayment of principal for mortgage-backed securities over a certain period of time. Loss Severity Percentage Rate, Maximum Loss severity, Maximum This element represents the maximum projected loss severity rate on loans, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities and estimated considering collateral characteristics. Loss Severity Percentage Rate, Minimum Loss severity, Minimum This element represents the minimum projected loss severity rate on loans, which is one of the assumptions used to evaluate other-than-temporary impairments on mortgage-backed securities and estimated considering collateral characteristics. U S Frozen Qualified Pension Plans Grandfathered Employees [Member] Grandfathered employees in frozen U.S. pension plans Represents small group of certain grandfathered employees who are still accruing benefits under a final pay plan formula while the U.S. qualified pension plan was frozen on January 1, 2008. Commissions and fees Fees and Commissions [Line Items] Defined Contribution Plan Eligible Employees for Fixed Employer Contribution Maximum Compensation Maximum compensation to be eligible for fixed contribution from employer Represents the maximum compensations of employees to be eligible to receive the fixed contributions from employer. Schedule of Changes in Goodwill [Table Text Block] Tabular disclosure changes of goodwill in details and total. Disclosure details may include, but are not limited to, the carrying amount of goodwill, goodwill acquired during the year, goodwill impairment losses recognized, goodwill written-off due to the sale of a business unit, goodwill not yet allocated, and any other changes to goodwill. Changes in Goodwill Goodwill Written Off Related To Discontinued Operations Discontinued Operations Write-off of the carrying amount of goodwill associated with discontinued operations in the period. Schedule of Sensitivity of Adverse Changes Discount Rate on Collateralized Debt Obligations and Collateralized Loan Obligations [Table Text Block] Schedule of sensitivity of adverse changes of 10% and 20% to discount rate, CDOs and CLOs This element represents the schedule of sensitivity of adverse changes of 10% and 20% to the discount rate for CDOs and CLOSs. Expiration Date 2021 [Member] 2021 This element represents the expiration date of operating loss carry-forwards and tax credit carry-forwards in 2021. Expiration Date 2012 [Member] 2012 This element represents the expiration date of operating loss carry-forwards and tax credit carry-forwards in 2012. This element represents the expiration date of operating loss carry-forwards and tax credit carry-forwards in 2030. 2030 Expiration Date 2030 [Member] This element represents the expiration date of operating loss carry-forwards and tax credit carry-forwards in 2031. 2031 Expiration Date 2031 [Member] Various Expiration Date [Member] Various This element represents operating loss carryforwards and tax credit carryforwards with various expiration date. Postemployment Benefits [Abstract] Postemployment Plans Funded status recognized Postemployment Benefits Liability Net expense recognized in the consolidated statement of income Postemployment Benefits, Period Expense Postemployment Benefits Accumulated Other Comprehensive Income Net Transition Assets Obligations Represents the amount of net transition obligation which has yet to be recognized as components of postemployment cost. Net transition obligation Deferred Tax Assets Tax Carryforwards Related to Companies Filing Separate Tax Returns The tax effect as of the balance sheet date of the amount of future tax effects arising from tax carryforwards related to companies that file U.S. federal tax returns separate from Citigroup's consolidated U.S. federal tax return. Tax carryforwards related to companies that file U.S. federal tax separate from Citigroup's consolidated U.S. federal tax return Total C G B And L C L [Member] Represents the total CGB and Local Consumer Lending (LCL). Total CGB and LCL National Mortgage Settlement [Member] Represents the national mortgage settlement. National Mortgage Settlement Number of States Represents the number of states. Number of states Cash Payments Payable to States and Federal Agencies Represents the cash payments payable to the States and federal agencies, which will be used for payments to homeowners affected by foreclosure practices. Cash payments payable to the States and federal agencies Loan Modifications for Delinquent Borrowers Represents the amount of loan modifications for delinquent borrowers as a form of customer relief. Loan modifications for delinquent borrowers Period of Loan Modifications for Delinquent Borrowers Represents the period of loan modifications for delinquent borrowers as a form of customer relief. Period of loan modifications for delinquent borrowers (in years) Reduction in Interest Rate Value Represents the value of refinancing concessions in the form of reduction in interest rates. Refinancing concessions Reduction in Interest Rate Period Represents the period of refinancing concessions in the form of reduction in interest rates. Period of refinancing concessions (in years) Financial Consideration for National Represents the amount of total financial consideration for national mortgage settlement. Total financial consideration for national mortgage settlement Amount claimed by Citigroup entities Gain Contingency, Unrecorded Amount Bankruptcy Claim Clearing Obligations Amount to Avoid from Setoff Represents the amount of setoff to be avoided. Amount of setoff to be avoided Bankruptcy Claim Clearing Obligations Amount to Avoid from Setoff Related to Terminated Derivatives Contracts Represents the amount of setoff to be avoided relating to terminated derivatives contracts. Amount of setoff to be avoided relating to terminated derivatives contracts Loans And Leases Receivable Real Estate Acquired Through Foreclosure Policy Other Real Estate Owned and Repossessed Assets Fair Value Assets Measured on Nonrecurring Basis Changes [Text Block] Tabular disclosure of total nonrecurring fair value measurements for the period, included in earnings, attributable to the change in fair value relating to assets that are still held as of the reporting date. Changes in total nonrecurring fair value measurements Proceeds from Dividends Received from Citibank Dividend received from Citibank Dividends that Citigroup received from Citibank during the current period. Cash Flows Between Transferor and Transferee [Abstract] Cash Flows Between Transferor and Transferee Key assumptions used in measuring fair value of retained interests at date of sale or securitization of mortgage receivables Assumptions for Fair Value on Securitization Date of Interests Continued to be Held by Transferor Servicing Assets or Liabilities [Abstract] Assumption for Fair Value on Securitization Date of Interests Continued to be Held by Transferor Servicing Assets or Liabilities Weighted Average Discount Rate Weighted average discount rate, date of sale or securitization (as a percent) The weighted average discount rate which is used to value residual cash flows generated by financial assets of the securitization, asset-backed financing arrangement, or similar transfer. This is used as a key assumption in measuring the fair value of assets or liabilities that relate to a transferor's assets obtained or liabilities incurred, if any, at the time of securitization, asset-backed financing, or similar transfer. Assumption for Fair Value on Securitization Date of Interests Continued to be Held by Transferor Servicing Assets or Liabilities Weighted Average Anticipated Credit Losses The weighted average rate at which principal will not be repaid on securitized financial assets, including expected static pool losses. This is used as a key input and assumption in measuring the fair value of assets obtained or liabilities incurred that relate to a transferor's continuing involvement, if any, at the time of securitization, asset-backed financing, or similar transfer. Weighted average anticipated net credit losses, date of sale or securitization (as a percent) Assumptions for Fair Value of Interests Continued to be Held by Transferor Servicing Assets or Liabilities [Abstract] Key assumptions used in measuring fair value related to transferor's continuing involvement Assumption for Fair Value of Interests Continued to be Held by Transferor Servicing Assets or Liabilities Weighted Average Discount Rate The weighted average discount rate which is used to value residual cash flows generated by financial assets of a securitization, asset-backed financing arrangement, or similar transfer. This is used as a key input and assumption in measuring the fair value of assets or liabilities that relate to a transferor's continuing involvement, if any, as of the date of the latest statement of financial position presented. Weighted average discount rate, transferor's continuing involvement (as a percent) Assumption for Fair Value of Interests Continued to be Held by Transferor Servicing Assets or Liabilities Weighted Average Prepayment Speed Weighted average estimated speed of prepayments of principal on financial assets. This is used as a key input and assumption in measuring the fair value of assets or liabilities that relate to a transferor's continuing involvement, if any, as of the date of the latest statement of financial position presented. Weighted average constant prepayment rate, transferor's continuing involvement (as a percent) Assumption for Fair Value of Interests Continued to be Held by Transferor Servicing Assets or Liabilities Weighted Average Anticipated Credit Losses The weighted average rate at which principal will not be repaid on securitized financial assets. This is used as a key input and assumption in measuring the fair value of assets or liabilities that relate to a transferor's continuing involvement, if any, as of the date of the latest statement of financial position presented. Weighted average anticipated credit losses, transferor's continuing involvement (as a percent) Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor [Abstract] Sensitivity analysis of fair value of interests continued to be held by transferor Total MSR fees Fees and Commissions, Mortgage Banking and Servicing Weighted average life (in years) Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities, Weighted Average Life Other Investment Receivables [Member] Other investment receivables Represents the information related to other investment receivables. Structured Reverse Repos to be Classified Level Three Mature Period, Minimum Represents minimum mature period for structured reverse repos to be classified as Level 3. Minimum mature period for structured reverse repos to be classified as Level 3 (in years) Funded Letters of Credit Past Due or on Nonaccrual Status Period, Maximum Maximum period in which funded letter of credit is past due or on non-accrual status. Maximum period funded letters of credit past due or on non-accrual status (in days) Deferred Tax Assets, Change in Enacted Tax Rate The tax effect as of the balance sheet date of the amount of the estimated future tax deductions attributable to change in enacted tax rate, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Effect of Japan tax rate change Reduction in gross uncertain tax positions Represents the amount of decrease in gross uncertain tax positions resulting from conclusion of New York City audit for 2006-2008. Unrecognized Tax Benefits Decrease Resulting from Uncertain Periodic Tax Positions Deferred Tax Liabilities, Debt Valuation Adjustment on Liabilities The amount as of the balance sheet date of the estimated future tax effects attributable to debt valuation adjustments on the entity's liabilities. Debt valuation adjustments on Citi liabilities Morgan Stanley Smith Barney Joint Venture [Member] Morgan Stanley Smith Barney joint venture (MSSB) Represents the equity method investment in Morgan Stanley Smith Barney joint venture (MSSB). Equity Method Investment Temporary Impairment Temporary impairment to equity method investments This item represents temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. Equity Method Investment Additional Cumulative Pretax Losses Additional cumulative pretax loss on equity method investments Represents the amount of additional cumulative pretax loss arising due to foreign currency translation and related hedges. Carrying value of equity method investment Equity Method Investments Schedule of Equity Method Investment, Equity Method Investee, Name [Axis] Equity Method Investee, Name [Domain] Cash Held as Collateral Cash collateral available to reimburse losses realized under guarantees and indemnifications Cash held as collateral available to the reporting entity to reimburse losses realized under guarantees and indemnifications. Increase (Decrease) on Other Operating Expenses before Tax Due to Settlement Residential Loan Related Investigations with Government Increase (decrease) on other operating expenses before tax due to additional charge Represents increase or decrease on other operating expenses before tax due to additional charge to settle with U.S. Federal government agencies and state attorneys a number of related investigations into residential loan servicing and origination practices. Increase (Decrease) on Diluted Earnings Per Share Due to Settlement Residential Loan Related Investigations with Government Represents increase or decrease on diluted earnings per share due to additional charge to settle with U.S. Federal government agencies and state attorneys a number of related investigations into residential loan servicing and origination practices. Increase (decrease) on diluted earnings per share due to the additional charge Number of Equity Method Investments Represents the number of equity method investments owned by entity. Number of equity method investments Cumulative effect of initial adoption of new accounting principle on beginning retained earnings, net of tax. This element can be used, generally, for the adjustment to retained earnings of a new accounting principle adoption. Cumulative Effect of Initial Adoption of New Accounting Change in opening retained earning Netting, cash collateral paid Derivative Liability, Fair Value, Amount Offset Against Collateral Netting, cash collateral received Derivative Asset, Fair Value, Amount Offset Against Collateral Transfer of Investments Transfers to trading accounting assets from investments (available for sale) Transfer Of Held To Maturity Investments Transfers to trading accounting assets from investments (held-to-maturity) Value of held-to-maturity investments transferred in noncash transactions. Stock Issued During Period, Value, Treasury Stock Reissued Issuance of shares pursuant to employee benefit plans Service period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period Deferred Compensation Arrangements by Plan Type Period of Restriction for Sale of Shares Paid to U K Participant The period of restriction for the sale of shares paid to U.K participant's, as stated in months. Period of restriction for the sale of shares paid to U. K. participants (in months) Long Term Care Insurance Indemnification [Member] Long-Term Care Insurance Indemnification Represents the long-term care insurance indemnification. GUARANTEES AND COMMITMENTS Business combinations BUSINESS DIVESTITURES Other Related Litigation Matters [Member] ASTA/MAT- and Falcon-Related Litigation and Other Matters Represents other related litigation matters. Net Investment Hedging [Member] Net investment hedge Net Investment Hedges Trading Activity, by Type [Domain] Trading Activity [Axis] Trading Derivatives [Member] Trading derivatives A group of derivative instruments held for trading purposes. Derivative [Line Items] Derivatives Notional Amount of Derivatives Derivative notionals Derivative, Collateral, Right to Reclaim Cash Cash collateral paid, net of amount used to offset derivative liabilities Derivative, Collateral, Obligation to Return Cash Cash collateral received, net of amount used to offset derivative assets Cash Flow Hedging [Member] Cash Flow Hedges Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship Summary of Derivative Instruments by Hedge Designation [Abstract] Pretax change in accumulated other comprehensive income (loss) Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net Effective portion of hedges included in AOCI Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Effective portion of cash flow hedges reclassified from AOCI to earnings U S [Member] U.S. Scenario, Adjustment Scenario, Adjustment [Member] Deferred Policy Acquisition Cost and Present Value of Future Profits Amortization Expense Amortization of deferred policy acquisition costs and present value of future profits Amount of deferred policy acquisition costs and capitalized present value of future profits (also known as VOBA) charged to expense in the period, generally in proportion to related revenue earned, estimated gross profits, or over the customer relationship or some other period. (Additions)/reductions to deferred policy acquisition costs Deferred Policy Acquisition Costs, Period Increase (Decrease) CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME Increase (Decrease) in Other Operating Assets Change in other assets Change in other liabilities Increase (Decrease) in Other Operating Liabilities Other comprehensive income attributable to noncontrolling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest [Abstract] Total other comprehensive income attributable to noncontrolling interests Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Impairment charge related to total investment, pre-tax Asset Impairment Charges Impairment charge related to Citi's investment in Akbank The amount of outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings. Outstanding Recorded Investment Related to Financing Receivables Deferred principal Financing Receivables Contingent Principal Forgiven Represents the amount of financing receivables' contingent principal forgiven by the holder of the instrument. Contingent principal forgiveness Financing Receivables, Troubled Debt Restructuring, Average Payment Relief Represents the percentage of average payment relief given under troubled debt restructurings. Average % payment relief Financing Receivables Troubled Debt Restructuring Average Interest Rate Reduction Represents the average interest rate reduction given under troubled debt restructurings. Average interest rate reduction (as a percent) Financing Receivables Number of Contracts Represents the number of financing receivables that were modified within the last 12 months prior to each quarter end in the current fiscal year. Number of loans Number of Days Past Due for Default Status Represents the classified default number of days for which the loan is past due. Number of days past due, default status (in days) Financing Net Reported Amount Distressed Loan Purchased Represents the carrying amount of the purchased distressed loan portfolio as of balance sheet date. Purchased distressed loan portfolio, carrying amount Financing Receivable Distressed Loan Purchased Allowance Represents the allowance relating to purchased distressed loan portfolio as of balance sheet date. Purchased distressed loan portfolio, allowance Schedule of Carrying Amount of Financing Receivables by Valuation Method [Table] Represents the change in accretable yield, related allowance and carrying amount, net of accretable yield with reference to revenue recognition method used. Carrying Amount of Financing Receivables by Valuation Method [Axis] Represents the change in financing receivables with reference to the revenue recognition method used. Loans and Lease Receivables Valuation Methods [Domain] Represents revenue recognition methods used. Represents the level-yield method used for accounting of financing receivables. Level Yield Method [Member] Level-yield method Represents the cost-recovery method used for accounting of financing receivables. Cost Recovery Method [Member] Cost-recovery method Carrying Amount of Financing Receivables by Valuation Method [Line Items] Carrying amount of financing receivables by valuation method Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Accretable Yield Allowance Increase (Decrease) Increase (decrease) in allowance resulting in a change in the excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Builds (reductions) to the allowance Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Accretable Yield Expected Cash Flow Increase (Decrease) Increase (decrease) in loan's cash flows expected to be collected over the investor's initial investment in the loan for loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Increase to expected cash flows Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Accretable Yield Others Other increase (decrease), not specified elsewhere in the taxonomy, resulting in a change in the excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. FX/Other Carrying Amount of Loans Acquired in Transfer Not Accounted for as Debt Securities [Roll Forward] Carrying amount of loans acquired in transfer accounted for as debt securities Carrying Amount of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Additions Increases in the aggregate contractual rights to receive money on demand or on fixed or determinable dates (that is, loans) not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Purchases Carrying Amount of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Disposals of Loans Contractual rights to receive money on demand or on fixed or determinable dates (that is, loans) not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable, that are disposed off during the period. Disposals/payments received Carrying Amount of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Accretion Current period recognition due to accretion to contractual rights to receive money on demand or on fixed or determinable dates (that is, loans) not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Accretion Carrying Amount of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Expected Cash Flows Increase (Decrease) Increase (decrease) in net cash flows for contractual rights to receive money on demand or on fixed or determinable dates (that is, loans) not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Increase to expected cash flows Other increase (decrease) not specified elsewhere in the taxonomy, in contractual rights to receive money on demand or on fixed or determinable dates (that is, loans) not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Carrying Amount of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Others FX/other Carrying Amount of Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Allowance Increase (Decrease) Increase (decrease) in allowance for contractual rights to receive money on demand or on fixed or determinable dates (that is, loans) not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. Builds (reductions) to the allowance Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Allowance for Loan Losses [Roll Forward] Financing receivable allowance for credit losses Financing Receivable Allowance for Credit Losses, Other FX/other Other increase (decrease), not specified elsewhere in the taxonomy, in the allowance for credit losses related to financing receivables. Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Balance at the beginning of the period Balance at the end of the period Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion Accretion Purchases Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Additions Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans Disposals/payments received Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] Certain loans acquired in transfer accounted for as debt securities, accretable yield movement schedule Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net Balance at the beginning of the period Balance at the end of the period Financing Receivable, Allowance for Credit Losses Beginning balance Balance, December 31, 2010 Allowance for credit losses associated with loans modified under the ASU Financing Receivable, Allowance for Credit Losses, Charge-offs Builds (reductions) to the allowance Disposals/payments received Financing Receivable, Allowance for Credit Losses, Recoveries Financing Receivable, Modifications, Number of Contracts Number of loans modified Financing Receivable, Modifications, Pre-Modification Recorded Investment Pre-modification recorded investment Financing Receivable, Modifications, Post-Modification Recorded Investment Post-modification recorded investment Incremental Effect of New Accounting Pronouncement or Change in Accounting Principle on Deferred Acquisition Costs The incremental increase (decrease) in deferred acquisition costs resulting from the adoption of a new accounting pronouncement, as of the date of adoption of the pronouncement. Reduction in DAC due to change in change in accounting principle Reduction in deffered tax asset due to change in change in accounting principle Increase (Decrease) in Deferred Policy Acquisition Costs Change in opening retained earning Impact of Restatement on Opening Retained Earnings, Net of Tax INTEREST REVENUE AND EXPENSE Total revenues, net of interest expense Disposal Group, Including Discontinued Operation, Revenue Business Description and Basis of Presentation [Text Block] BASIS OF PRESENTATION Summarized financial information for Egg Banking PLC Credit Card Business Tabular disclosure relating to the sale of Egg Banking PLC Credit Card Business, which is classified as a discontinued operation. Schedule Of Disposal Groups Including Discontinued Operations Egg Banking P L C [Table Text Block] Deferred Portion Delivered as CAP Award Percentage Represents the percentage of deferred portion delivered as a CAP award. Percentage of deferred portion delivered as CAP award Deferred Cash Program [Member] Deferred Cash Program Represents the summary pertaining to deferred cash programs. Other-than-temporary-impairment loss Other than Temporary Impairment Losses, Investments, Available-for-sale Securities Equity Method Investment Ownership Percentage Maximum Maximum equity method investment ownership percentage Represents maximum percentage of ownership interest. Asset Impairment Charges After Tax Impairment charge related to total investment, after-tax The charge against earnings resulting from the aggregate write down of all assets from the carrying value to the fair value, after-tax. Other Asset [Member] Other assets Represents investments which are neither classified as available for sale nor held to maturity. Structured Reverse Repos to be Classified Level3 Mature Period, Minimum Minimum mature period for structured reverse repos to be classified as Level 3 (in years) Represents minimum mature period for structured reverse repos to be classified as Level 3. Fair Value Measurement With Unobservable Inputs Mortgage Servicing Rights Increase (Decrease) in Level 3 Due to Reduction in Interest Rates This element represents the increase (decrease) in the balance of mortgage servicing rights due to reduction in interest rates. Increase (decrease) in level 3 of mortgage servicing rights due to reduction in interest rates Fair Value Measurement With Unobservable Inputs Long-term Debt Scheduled Termination of Structured Transaction Increase (Decrease) in Level 3 Increase (decrease) in level 3 of Long-term debt due to scheduled termination of a structured transaction This element represents the increase (decrease) in the balance of long-term debt related to scheduled termination of a structured transaction at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Investment in Consolidated Variable Interest Entities Certificates Classified as Level 3 Investment in certificates issued by trusts of the newly consolidated VIE's that were classified as Level 3 This element represents the Company's investment in certificates issued by the trusts of the newly consolidated VIE's that were classified as Level 3 for fair value measurement purposes. Fair Value Assets and Liabilities Measured on Recurring and Non-recurring Basis Unobservable Input Reconciliation [Table Text Block] Tabular disclosure of the fair value measurement of assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets and liabilities) and gains or losses recognized in other comprehensive income, and a description of where those gains or losses included in earnings (or changes in net assets and liabilities) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset and liability. Significant valuation techniques and most significant unobservable inputs used in Level 3 fair value measurements Valuation Technique [Axis] Information by valuation technique. Valuation Technique [Domain] Valuation techniques used by the entity. Cash flow Valuation Technique [Member] Cash flow Cash flow valuation technique used to measure fair value. Price Based Valuation Technique [Member] Price-based Price-based valuation technique used to measure fair value. Internal Model Valuation Technique [Member] Internal Model Internal model valuation technique used to measure fair value. Broker Quotes Valuation Technique [Member] Broker Quotes Broker quotes valuation technique used to measure fair value. Yield Analysis Valuation Technique [Member] Yield Analysis Yield analysis valuation technique used to measure fair value. Third Party Valuation, Valuation Technique [Member] Third Party Valuation Third party valuation, a technique used to measure fair value. External Model Valuation Technique [Member] External Model External model valuation technique used to measure fair value. Consensus Pricing Valuation Technique [Member] Consensus Pricing Consensus pricing valuation technique used to measure fair value. Comparables Analysis Valuation Technique [Member] Comparables Analysis Comparables analysis valuation technique used to measure fair value. Fair Value Inputs Interest Rate Represents the interest rate, used as an input to measure fair value. Interest Rate (as a percent) Fair Value Inputs Yield Represents the yield, used as an input to measure fair value. Yield (as a percent) Fair Value Inputs Discount Rate Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt. Discount Margin (as a percent) Fair Value Inputs Prepayment Rate Rate at which loans or a loan portfolio are expected to prepay principal balances, used as an input to measure fair value. Prepayment Rate (as a percent) Fair Value Inputs Price Price Represents the commodity price, such as equity prices or oil prices, used as an input to measure fair value. Fair Value Inputs Adjusted Yield Adjusted Yield (as a percent) Represents the adjusted yield, used as an input to measure fair value. Fair Value Inputs Bid Offer Bid-Offer Represents the bid-offer of broker quotes, used as an input to measure fair value. Fair Value Inputs Rate of Inflation Inflation Rate The rate of inflation, used as an input to measure fair value. Fair Value Inputs Constant Default Rate CDR (as a percent) Represents the constant default rate, used as an input to measure fair value. Fair Value Inputs Recovery Rate Recovery Rate (as a percent) Represents the recovery rate, used as an input to measure fair value. Fair Value Inputs Weighted Average Life WAL Represents the weighted average life, used as an input to measure fair value. Fair Value Inputs Fund Net Asset Value Fund NAV Represents the fund net asset value, used as an input to measure fair value. Fair Value Inputs Credit Correlation Credit Correlation Represents the credit correlation used as an input to measure fair value. Fair Value Inputs Foreign Exchange Volatility FX Volatility (as a percent) Represents the foreign exchange volatility used as an input to measure fair value. Fair Value Inputs Interest Rate Foreign Exchange Correlation IR-FX Correlation Represents the interest rate foreign exchange correlation used as an input to measure fair value. Fair Value Inputs Interest Rate Correlation IR-IR Correlation Represents the interest rate correlation used as an input to measure fair value. Fair Value Inputs Interest Rate Volatility IR Volatility (as a percent) Represents the interest rate volatility used as an input to measure fair value. Fair Value Inputs Interest Rate Volatility Skew IR Volatility Skew Represents the interest rate volatility skew used as an input to measure fair value. Fair Value Inputs Mean Reversion Mean Reversion Represents the mean reversion used as an input to measure fair value. Fair Value Inputs Foreign Exchange Credit Correlation FX-Credit Correlation Represents the foreign exchange credit correlation used as an input to measure fair value. Fair Value Inputs Equity Volatility Equity Volatility Represents the standard deviation in equity price used as an input to measure fair value. Fair Value Inputs Credit Spread Volatility Credit Spread Volatility Represents the standard deviation of spread between treasury securities and non-treasury securities used as an input to measure fair value. Fair Value Inputs Equity Forward Equity Forward Represents the derivative contract for the purchase of an individual stock, a stock portfolio or a stock index at some future date used as an input to measure fair value. Fair Value Inputs Equity Correlation Equity-Equity Correlation Represents the statistical measure of how two equity securities move in relation to each other used as an input to measure fair value. Fair Value Inputs Equity Foreign Exchange Correlation Equity-FX Correlation Represents the correlation between equity and foreign exchange used as an input to measure fair value. Fair Value Inputs Yield Volatility Yield Volatility Represents the standard deviation in yield used as an input to measure fair value. Fair Value Inputs Commodity Correlation Commodity Correlation Represents the statistical measure of how two commodity prices move in relation to each other used as an input to measure fair value. Fair Value Inputs Commodity Volatility Commodity Volatility (as a percent) Represents the standard deviation in commodity prices used as an input to measure fair value. Fair Value Inputs Forward Price Forward Price Represents the investment company's price for their buy and sell orders of fund used as an input to measure fair value. Fair Value Inputs Credit Spread Credit Spread (as a percent) Represents the rate of financial derivative contract that transfers credit risk from one party to another, used as an input to measure fair value. Fair Value Inputs Inventory Points Inventory Points Represents the inventory points, used as an input to measure fair value. Fair Value Inputs Underlying Reference Asset Price Underlying reference asset price Represents the underlying reference asset price, used as an input to measure fair value. Fair Value Inputs Consensus Price Consensus Price Represents the consensus price, used as an input to measure fair value. Fair Value Inputs Earnings before Interest Taxes Depreciation and Amortization Multiple EBITDA multiples Represents the earnings before interest, taxes, depreciation and amortization multiple, used as an input to measure fair value. Fair Value Inputs Adjustment Factor Adjustment factor Represents the adjustment factor, used as an input to measure fair value. Fair Value Inputs Redemption Rate Redemption Rate (as a percent) Represents the redemption rate of financial securities, used as an input to measure fair value. Fair Value Inputs Equity Interest Rate Correlation Equity-IR Correlation Represents the equity interest rate correlation, used as an input to measure fair value. Fair Value Inputs Equity Commodity Correlation Equity-Commodity Correlation Represents the statistical measure of how commodity prices and equity prices move in relation to each other used as an input to measure fair value. Fair Value Inputs Interest Rate Basis Volatility IR Basis Volatility Represents the interest rate basis volatility used as an input to measure fair value. Fair Value Inputs Assets Liabilities Quantitative Information Fair Value Inputs Assets Liabilities Quantitative Information [Line Items] Schedule of Amounts Recognized in Principal Transactions Related to Derivative Instruments and Non Derivative Instruments [Table Text Block] Schedule of amounts recognized in Principal transactions in the Consolidated Statement of Income related to derivatives not designated in a qualifying hedging Tabular disclosure of gains and losses which were recognized in Principal transactions in the Consolidated Statement of Income related to derivatives not designated in a qualifying hedging relationship and underlying non-derivative instruments. Fair Value by Asset Class [Axis] Fair Value by Liability Class [Axis] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain] Fair Value, Liabilities, Measured on Recurring Basis, Unobservable Input Reconciliation, by Liability Class [Domain] Realized gains (losses) on sales of investments, net Net realized gains Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments Schedule of Investments Summary Investment Holdings [Table Text Block] Fair value of available-for-sale securities in unrealized loss position Schedule of Unrealized Loss on Investments [Table Text Block] Amortized cost and fair value of debt securities available-for-sale by contractual maturity dates Investments Classified by Contractual Maturity Date [Table Text Block] Gross realized investment gains Available-for-sale Securities, Gross Realized Gains Gross realized investment losses Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments Alternative investment funds, fair value Alternative Investments, Fair Value Disclosure Alternative investment funds, unfunded commitments Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments Number Of Common Stocks Issued To Convert Equity Units Number of common stocks issued to convert equity units Number of common stocks were issued to convert the equity units during the period. Schedule of loans Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Deferred Compensation Arrangements by Plan Type [Axis] Disclosures related to the types of deferred compensation plans that are offered to a group of employees that are intended to be paid in cash unless required. Type of Deferred Compensation [Domain] Key Employee Profit Sharing Plan 2011 and Key Risk Employee Plan [Member] This element represents details pertaining to 2011 Key Employee Profit Sharing Plan (KEPSP) and Key Risk Employee Plan (KREP). KEPSP and KREP Deposits by Geographic Area [Axis] Interest-bearing deposits, at fair value Deposits, Fair Value Disclosure Change in net unrealized gains (losses) on investment securities, net of taxes Net change in unrealized gains and losses on investment securities, net of taxes Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Foreign currency translation adjustment, net of taxes Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Net change in foreign currency translation adjustment, net of taxes and hedges Cash flow hedges, net of taxes Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent Net change in cash flow hedges, net of taxes Pension liability adjustment, net of taxes Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent Change Other comprehensive income before attribution of noncontrolling interest Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income, Reclassification Adjustment for Sale and Write-down of Securities Included in Net Income, Net of Tax, Portion Attributable to Parent Reclassification adjustment for write-down and unrealized gains or losses realized upon the sale of securities, after tax attributable to the parent entity. Reclassification after tax realized gains or losses on sales and impairments of securities Private Banking Loans [Member] Represents financing receivables classified as Private Banking loans. Private Banking loans Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest Net change in unrealized gains and losses on investment securities, net of tax Net change in FX translation adjustment, net of tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Noncontrolling Interest Accumulated other comprehensive income-net change in unrealized gains and losses on investment securities, net of tax Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Net change in cash flow hedges, net of taxes Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Accumulated other comprehensive income (loss)-net change in foreign currency translation adjustment, net of tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Short-term borrowings This element represents the short-term borrowings of the variable interest entity. Short Term Borrowings In Variable Interest Entity This element represents the carrying amount of other liabilities of the variable interest entity. Other liabilities Other Liabilities in Variable Interest Entity Assumption for Fair Value on Securitization Date of Interests Continued to be Held by Transferor Servicing Assets or Liabilities Weighted Average Prepayment Speed The weighted average estimated speed of prepayments of principal on financial assets. This is used as a key assumption in measuring the fair value of assets obtained or liabilities incurred that relate to a transferor's continuing involvement, if any, at the time of securitization, asset-backed financing, or similar transfer. Weighted average constant prepayment rate, date of sale or securitization (as a percent) Fair Value of Re-securitizations Deals in which Entity Holds Retained Interest Represents the fair value of re-securitizations deals in which entity holds retained interest. Fair value of re-securitizations deals in which the entity holds a retained interest Original Par Value of Securities Transferred to Re-securitization Entities Represents the amount of original par value of securities transferred to re-securitization entities. Original par value of securities transferred to re-securitization entities Entity Consolidated Administered Asset-backed Commercial Paper Conduit [Member] Citi-administered asset-backed consolidated commercial paper conduits (ABCP) This element represents entity-administered asset-backed consolidated commercial paper conduits. Entity Unconsolidated Administered Asset-backed Commercial Paper Conduit [Member] Citi-administered asset-backed unconsolidated commercial paper conduits (ABCP) This element represents entity-administered asset-backed unconsolidated commercial paper conduits. Deferred Compensation Arrangements Additional Waiting Period for Deferred Cash Awards Represents the additional waiting period for deferred cash awards. Additional waiting period for deferred cash awards Variable Interest Entity Cashflows Received on Retained Interest and Other Net Cash flows Cash flows received on retained interest and other net cash flows Represents cash flows received on retained interest and other net cash flows. Parent Company Accumulated Other Comprehensive Income [Member] Citigroup accumulated other comprehensive income (loss) Accumulated change in equity of parent company from transactions and other events and circumstances from non-owner sources at fiscal year-end. Excludes Net Income or Loss, and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, and unrealized gains and losses on certain investments in debt and equity securities as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. Transfers into Level 3, assets Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Transfers out of Level 3, assets Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Transfers into Level 3, liabilities Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3 Transfers out of Level 3, liabilities Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3 Fair Value Measurement with Unobservable Inputs Assets Transferred to Level Two from Level One Transfers from Level 1 to Level 2 This element represents the transfers into Level 2 of assets measured at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Fair Value Measurement with Unobservable Inputs Assets Transferred to Level One from Level Two Transfers from Level 2 to Level 1 This element represents the transfers into Level 1 of assets measured at fair value on a recurring basis using unobservable inputs, which have taken place during the period. Fair Value Inputs Prepayment Period Prepayment period Represents the prepayment period used as an input to measure fair value. Fair Value Inputs Underlying Price Underlying price(s) Represents the underlying price used as an input to measure fair value. Fair Value Inputs IR Basis IR Basis Represents the interest rate basis used as an input to measure fair value. Total assets Assets of discontinued operations held for sale Assets of discontinued operations at time of sale Assets of Disposal Group, Including Discontinued Operation Deferred Compensation Arrangements by Plan Type Period of Restriction for Sale of Shares Paid to Participants in European Union Period of restriction for the sale of shares paid to participants in the European Union (EU) (in months) The period of restriction for the sale of shares paid to identified staff in the European Union (EU), as stated in months. 2011 Key Employee Profit Sharing Plan (KEPSP) Deferred Profit Sharing [Member] Postemployment Plans [Member] Postemployment Plans Postemployment plans that provide income continuation and health and welfare benefits to certain eligible U.S. employees on a ling-term disability. Amount of settlement Loss Contingency, Settlement Agreement, Consideration Trading and Investments Securities [Member] Trading and investment securities Resents information in the aggreagate for marketable securities classified either as trading securities or available-for-sale securities and non-marketable equity securities that are carried at fair value. Loans and Leases [Member] Loans and leases Represents the information pertaining to the loans and leases. Short-term and Long-term Debt [Member] Short-term borrowings and long-term debt Represents a debt arrangement having an initial term within one year or the normal operating cycle, if longer. It also represents a debt arrangement having an initial term longer than one year or beyond the normal operating cycle, if longer. One to Four Family Residential Mortgages Commitment [Member] A one- to four-family residential mortgage commitment is a written confirmation from Citigroup to a seller of a property that the bank will advance the specified sums enabling the buyer to complete the purchase. One-to four-family residential mortgages Loss on Litigation Settlement The amount to which the entity settled to resolve the legal matter. Amount of settlement Other Comprehensive Income, Impact of Realized Gains from Sales of Minority Investments Net of Tax Portion Attributable to Parent Reclassification adjustment for realized gains from sales of minority investments, after tax attributable to the parent entity. After tax realized gains from sales of minority investments Housing Development Finance Corporation Ltd. [Member] Represents the investment in Housing Development Finance Corporation Ltd. (HDFC). HDFC Shanghai Pudong Development Bank [Member] Represents the investment in Shanghai Pudong Development Bank (SPDB). SPDB Other Financial Assets and Liabilities [Member] Nontrading derivatives and other financial assets and liabilities measured on a recurring basis (gross) This element represents the financial assets and liabilities not otherwise disclosed separately. Fair Value Measurement with Unobservable Inputs Reconciliation Recurring Basis Asset Gain (Loss) on Index Positions Classified as Level two Represents total gains or losses during the period arising from index positions classified as Level two. Gains on index positions classified as Level 2 Schedule of Guarantor Obligations by Expiration Date, Amount Outstanding and Carrying Value Schedule of Guarantor Obligations [Table Text Block] Commodity Contract [Member] Commodity contracts Commodity and other contracts Fair Value Inputs, Assets and Liabilities, Quantitative Information [Table] Schedule of the combined disclosure of the inputs and valuation techniques used to measure fair value, and a discussion of changes in valuation techniques and related inputs, if any, applied during the period to each separate class of assets and liabilities that are measured on a recurring and/or nonrecurring basis. Cash and Cash Equivalents, Period Increase (Decrease) Change in cash and due from banks Loans held-for-sale Loans Held-for-sale, Fair Value Disclosure Other real estate owned Real Estate Acquired Through Foreclosure Assets Fair Value, Disclosure Excluding Loans Held for Investment, Carrying Value Based on Collateral Fair Value This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity, excluding loans held for investment whose carrying amount is based on the fair value of the underlying collateral. Total assets at fair value on a nonrecurring basis excluding loans held for investment Financial Instruments not Carried at Fair Value [Member] This item represents the amount as included on the statement of financial position for the financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined) which are not carried at fair value. This item excludes items measured at fair value on a recurring basis but may include items measured at fair value on a nonrecurring basis. Financial instruments not carried at Fair Value Loans Receivable Excluding Lease Finance Receivables [Member] An amount of money or property, or a portion thereof, leant to a borrower (debtor) in exchange for a promise to repay the amount borrowed plus interest at a date certain in the future. Excludes lease finance receivables. Loans, excluding lease finance receivables Fair Value Additional Disclosures [Abstract] Fair value measurements additional disclosures Carrying Value Less than in Excess of Fair Value The amount by which the carrying value of a financial instrument is less than or greater than the fair value. Aggregate carrying value in excess of (less than) fair value Impairment charge related to Citi's investment in Akbank Impairment Charge Related To Investment The impairment charge against earnings resulting from the aggregate write down of an investment from their carrying value to their fair value.