BASIS OF PRESENTATION AND ACCOUNTING CHANGES (Policies)	6 Months Ended
Jun. 30, 2015
Accounting Policies [Abstract]
Accounting Changes	ACCOUNTING CHANGES Accounting for Investments in Tax Credit Partnerships In January 2014, the FASB issued Accounting Standards Update (ASU) No. 2014-01, Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects. Any transition adjustment is reflected as an adjustment to retained earnings in the earliest period presented (retrospective application). The ASU is applicable to Citi’s portfolio of low income housing tax credit (LIHTC) partnership interests. The new standard widens the scope of investments eligible to elect to apply a new alternative method, the proportional amortization method, under which the cost of the investment is amortized to tax expense in proportion to the amount of tax credits and other tax benefits received. Citi qualifies to elect the proportional amortization method under the ASU for its entire LIHTC portfolio. These investments were previously accounted for under the equity method, which resulted in losses (due to amortization of the investment) being recognized in Other revenue and tax credits and benefits being recognized in the Income tax expense line. In contrast, the proportional amortization method combines the amortization of the investment and receipt of the tax credits/benefits into one line, Income tax expense. Citi adopted ASU 2014-01 in the first quarter of 2015. The adoption of this ASU was applied retrospectively and cumulatively reduced Retained earnings by approximately $349 million, Other assets by approximately $178 million, and deferred tax assets by approximately $171 million. Accounting for Repurchase-to-Maturity Transactions In June 2014, the FASB issued ASU No. 2014-11, Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures. The ASU changes the accounting for repurchase-to-maturity transactions and linked repurchase financings to secured borrowing accounting, which is consistent with the accounting for other repurchase agreements. The ASU also requires disclosures about transfers accounted for as sales in transactions that are economically similar to repurchase agreements (see Note 21 to the Consolidated Financial Statements) and about the types of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings (see Note 10 to the Consolidated Financial Statements). The ASU’s provisions became effective for Citi from the first quarter of 2015, with the exception of the collateral disclosures which are effective in the second quarter of 2015. The effect of adopting the ASU is required to be reflected as a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. Adoption of the ASU did not have a material effect on the Company’s financial statements. Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure In August 2014, the FASB issued ASU No. 2014-14, Receivables-Troubled Debt Restructuring by Creditors (Subtopic 310-40): Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure, which requires that a mortgage loan be derecognized and a separate other receivable be recognized upon foreclosure if the following conditions are met: (i) the loan has a government guarantee that is not separable from the loan before foreclosure; (ii) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim; and (iii) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. Upon foreclosure, the separate other receivable is measured based on the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. Citi early adopted the ASU on a modified retrospective basis in the fourth quarter of 2014, which resulted in reclassifying approximately $130 million of foreclosed assets from Other Real Estate Owned to a separate other receivable that is included in Other assets. Given the modified retrospective approach to adoption, prior periods have not been restated. Disclosures for Investments in Certain Entities That Calculate Net Asset Value (NAV) per Share In May 2015, the FASB issued ASU No. 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent), which is intended to reduce diversity in practice related to the categorization of investments measured at NAV within the fair value hierarchy. The ASU removes the current requirement to categorize investments for which fair value is measured using the NAV per share practical expedient within the fair value hierarchy. Citi elected to early adopt the ASU in the second quarter of 2015. The adoption of the ASU was applied retrospectively and reduced Level 3 assets by $1.0 billion and $1.1 billion as of June 30, 2015 and December 31, 2014, respectively. FUTURE APPLICATION OF ACCOUNTING STANDARDS Revenue Recognition In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in GAAP when it becomes effective on January 1, 2018. Early application is permitted for annual periods beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that ASU 2014-09 will have on its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its financial statements. Consolidation In February 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis, which is intended to improve certain areas of consolidation guidance for legal entities such as limited partnerships, limited liability companies, and securitization structures. The ASU will reduce the number of consolidation models. The ASU will be effective on January 1, 2016. Early adoption is permitted, including adoption in an interim period. The Company is evaluating the effect that ASU 2015-02 will have on its Consolidated Financial Statements. Debt Issuance Costs In April 2015, the FASB issued ASU 2015-03, Interest— Imputation of Interest (Subtopic 835-30), Simplifying the Presentation of Debt Issuance Costs, to conform the presentation of debt issuance costs to that of debt discounts and premiums. Thus, the ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. The ASU will be effective for Citi on January 1, 2016 for both interim and annual periods and will be applied retrospectively to all periods presented. Early adoption is permitted for financial statements that have not been previously issued. The ASU is not expected to have a material effect on the Company. Accounting for Financial Instruments-Credit Losses In December 2012, the FASB issued a proposed ASU, Financial Instruments-Credit Losses. This proposed ASU, or exposure draft, was issued for public comment in order to allow stakeholders the opportunity to review the proposal and provide comments to the FASB and does not constitute accounting guidance until a final ASU is issued. The exposure draft contains proposed guidance developed by the FASB with the goal of improving financial reporting about expected credit losses on loans, securities and other financial assets held by financial institutions and other organizations. The exposure draft proposes a new accounting model intended to require earlier recognition of credit losses, while also providing additional transparency about credit risk. The FASB’s proposed model would utilize an “expected credit loss” measurement objective for the recognition of credit losses for loans, held-to-maturity securities and other receivables at the time the financial asset is originated or acquired and adjusted each period for changes in expected credit losses. For available-for-sale securities where fair value is less than cost, credit-related impairment would be recognized in the allowance for credit losses and adjusted each period for changes in credit. This would replace the multiple existing impairment models in GAAP, which generally require that a loss be “incurred” before it is recognized. The FASB’s proposed model represents a significant departure from existing GAAP, and may result in material changes to the Company’s accounting for financial instruments. The impact of the FASB’s final ASU on the Company’s financial statements will be assessed when it is issued. The exposure draft does not contain a proposed effective date; this would be included in the final ASU, when issued.

ACCOUNTING CHANGES

Accounting for Investments in Tax Credit Partnerships

In January 2014, the FASB issued Accounting Standards Update (ASU) No. 2014-01, Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects. Any transition adjustment is reflected as an adjustment to retained earnings in the earliest period presented (retrospective application).

The ASU is applicable to Citi’s portfolio of low income housing tax credit (LIHTC) partnership interests. The new standard widens the scope of investments eligible to elect to apply a new alternative method, the proportional amortization method, under which the cost of the investment is amortized to tax expense in proportion to the amount of tax credits and other tax benefits received. Citi qualifies to elect the proportional amortization method under the ASU for its entire LIHTC portfolio. These investments were previously accounted for under the equity method, which resulted in losses (due to amortization of the investment) being recognized in Other revenue and tax credits and benefits being recognized in the Income tax expense line. In contrast, the proportional amortization method combines the amortization of the investment and receipt of the tax credits/benefits into one line, Income tax expense.

Citi adopted ASU 2014-01 in the first quarter of 2015.

The adoption of this ASU was applied retrospectively and cumulatively reduced Retained earnings by approximately $349 million, Other assets by approximately $178 million, and deferred tax assets by approximately $171 million.

Accounting for Repurchase-to-Maturity Transactions

In June 2014, the FASB issued ASU No. 2014-11, Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures. The ASU changes the accounting for repurchase-to-maturity transactions and linked repurchase financings to secured borrowing accounting, which is consistent with the accounting for other repurchase agreements. The ASU also requires disclosures about transfers accounted for as sales in transactions that are economically similar to repurchase agreements (see Note 21 to the Consolidated Financial Statements) and about the types of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings (see Note 10 to the Consolidated Financial Statements). The ASU’s provisions became effective for Citi from the first quarter of 2015, with the exception of the collateral disclosures which are effective in the second quarter of 2015. The effect of adopting the ASU is required to be reflected as a cumulative effect adjustment to retained earnings as of the beginning of the period of adoption. Adoption of the ASU did not have a material effect on the Company’s financial statements.

Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure

In August 2014, the FASB issued ASU No. 2014-14, Receivables-Troubled Debt Restructuring by Creditors (Subtopic 310-40): Classification of Certain Government-Guaranteed Mortgage Loans upon Foreclosure, which requires that a mortgage loan be derecognized and a separate other receivable be recognized upon foreclosure if the following conditions are met: (i) the loan has a government guarantee that is not separable from the loan before foreclosure; (ii) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim; and (iii) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. Upon foreclosure, the separate other receivable is measured based on the amount of the loan balance (principal and interest) expected to be recovered from the guarantor.

Citi early adopted the ASU on a modified retrospective basis in the fourth quarter of 2014, which resulted in reclassifying approximately $130 million of foreclosed assets from Other Real Estate Owned to a separate other receivable that is included in Other assets. Given the modified retrospective approach to adoption, prior periods have not been restated.

Disclosures for Investments in Certain Entities That Calculate Net Asset Value (NAV) per Share

In May 2015, the FASB issued ASU No. 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent), which is intended to reduce diversity in practice related to the categorization of investments measured at NAV within the fair value hierarchy. The ASU removes the current requirement to categorize investments for which fair value is measured using the NAV per share practical expedient within the fair value hierarchy. Citi elected to early adopt the ASU in the second quarter of 2015. The adoption of the ASU was applied retrospectively and reduced Level 3 assets by $1.0 billion and $1.1 billion as of June 30, 2015 and December 31, 2014, respectively.

FUTURE APPLICATION OF ACCOUNTING STANDARDS

Revenue Recognition

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in GAAP when it becomes effective on January 1, 2018. Early application is permitted for annual periods beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that ASU 2014-09 will have on its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its financial statements.

Consolidation

In February 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis, which is intended to improve certain areas of consolidation guidance for legal entities such as limited partnerships, limited liability companies, and securitization structures. The ASU will reduce the number of consolidation models. The ASU will be effective on January 1, 2016. Early adoption is permitted, including adoption in an interim period. The Company is evaluating the effect that ASU 2015-02 will have on its Consolidated Financial Statements.

Debt Issuance Costs

In April 2015, the FASB issued ASU 2015-03, Interest— Imputation of Interest (Subtopic 835-30), Simplifying the Presentation of Debt Issuance Costs, to conform the presentation of debt issuance costs to that of debt discounts and premiums. Thus, the ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. The ASU will be effective for Citi on January 1, 2016 for both interim and annual periods and will be applied retrospectively to all periods presented. Early adoption is permitted for financial statements that have not been previously issued. The ASU is not expected to have a material effect on the Company.

Accounting for Financial Instruments-Credit Losses

In December 2012, the FASB issued a proposed ASU, Financial Instruments-Credit Losses. This proposed ASU, or exposure draft, was issued for public comment in order to allow stakeholders the opportunity to review the proposal and provide comments to the FASB and does not constitute accounting guidance until a final ASU is issued.

The exposure draft contains proposed guidance developed by the FASB with the goal of improving financial reporting about expected credit losses on loans, securities and other financial assets held by financial institutions and other organizations. The exposure draft proposes a new accounting model intended to require earlier recognition of credit losses, while also providing additional transparency about credit risk.

The FASB’s proposed model would utilize an “expected credit loss” measurement objective for the recognition of credit losses for loans, held-to-maturity securities and other receivables at the time the financial asset is originated or acquired and adjusted each period for changes in expected credit losses. For available-for-sale securities where fair value is less than cost, credit-related impairment would be recognized in the allowance for credit losses and adjusted each period for changes in credit. This would replace the multiple existing impairment models in GAAP, which generally require that a loss be “incurred” before it is recognized.

The FASB’s proposed model represents a significant departure from existing GAAP, and may result in material changes to the Company’s accounting for financial instruments. The impact of the FASB’s final ASU on the Company’s financial statements will be assessed when it is issued. The exposure draft does not contain a proposed effective date; this would be included in the final ASU, when issued.