BASIS OF PRESENTATION AND ACCOUNTING CHANGES (Policies)	9 Months Ended
Sep. 30, 2016
Accounting Policies [Abstract]
Accounting Changes	ACCOUNTING CHANGES Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. This ASU requires entities to present separately in OCI the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. It will also require equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income, thus eliminating eligibility for the current available-for-sale category. However, Federal Reserve Bank and Federal Home Loan Bank stock as well as exchange seats will continue to be presented at cost. Citi early-adopted only the provisions of this ASU related to presentation of the change in fair value of liabilities for which the fair value option was elected related to changes in Citigroup’s own credit spreads in OCI effective January 1, 2016. Accordingly, beginning in the first quarter 2016, these amounts of are reflected as a component of Accumulated other comprehensive income (AOCI), whereas, these amounts were previously recognized in Citigroup’s revenues and net income. The impact of adopting this amendment resulted in a cumulative catch-up reclassification from retained earnings to AOCI of an accumulated after tax loss of approximately $15 million at January 1, 2016. Financial statements for periods prior to 2016 were not subject to restatement under the provisions of this ASU. For additional information, see Note 17, Note 20 and Note 21 to the Consolidated Financial Statements. The Company is evaluating the effect that the other provisions of ASU 2016-01 will have on its Consolidated Financial Statements and related disclosures. FUTURE APPLICATION OF ACCOUNTING STANDARDS Income Tax Impact of Intra-Entity Transfers of Assets In October 2016, the FASB issued ASU No. 2016-16, Income Taxes - Intra-Entity Transfers of Assets Other Than Inventory, which will require an entity to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. The ASU is effective on January 1, 2018 with early adoption permitted. The Company is evaluating the effect that ASU 2016-16 will have on its Consolidated Financial Statements. Accounting for Financial Instruments-Credit Losses In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326). The ASU introduces a new accounting model, the Current Expected Credit Losses model (CECL), which requires earlier recognition of credit losses, while also providing additional transparency about credit risk. The FASB’s CECL model utilizes a lifetime “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. The expected credit losses are adjusted each period for changes in expected lifetime credit losses. For available-for-sale securities where fair value is less than cost, credit-related impairment, if any, will be recognized in an allowance for credit losses and adjusted each period for changes in expected credit risk. This model replaces the multiple existing impairment models in current GAAP, which generally require that a loss be incurred before it is recognized. The CECL model represents a significant departure from existing GAAP, and may result in material changes to the Company’s accounting for financial instruments. The Company is evaluating the effect that ASU 2016-13 will have on its Consolidated Financial Statements and related disclosures. The ASU will be effective for Citi as of January 1, 2020. Early application is permitted for annual periods beginning January 1, 2019. 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. The ASU is not applicable to financial instruments and, therefore, is not expected to impact a majority of the Company’s revenue, including net interest income. The Company plans to adopt the new revenue recognition guidance in the first quarter of 2018. The Company does not expect a material change in timing of revenue recognition and is evaluating the effect that ASU 2014-09 will have on the presentation of its Consolidated Financial Statements and related disclosures and its adoption method. Lease Accounting In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which is intended to increase transparency and comparability of accounting for lease transactions. The ASU will require lessees to recognize all leases on the balance sheet as lease assets and lease liabilities and will require both quantitative and qualitative disclosures regarding key information about leasing arrangements. Lessor accounting is largely unchanged. The guidance is effective beginning January 1, 2019 with an option to early adopt. The Company is evaluating whether to early adopt and the effect that ASU 2016-02 will have on its Consolidated Financial Statements, regulatory capital and related disclosures.

ACCOUNTING CHANGES

Recognition and Measurement of Financial Assets and Financial Liabilities

In January 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments.

This ASU requires entities to present separately in OCI the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. It will also require equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income, thus eliminating eligibility for the current available-for-sale category. However, Federal Reserve Bank and Federal Home Loan Bank stock as well as exchange seats will continue to be presented at cost.

Citi early-adopted only the provisions of this ASU related to presentation of the change in fair value of liabilities for which the fair value option was elected related to changes in Citigroup’s own credit spreads in OCI effective January 1, 2016. Accordingly, beginning in the first quarter 2016, these amounts of are reflected as a component of Accumulated other comprehensive income (AOCI), whereas, these amounts were previously recognized in Citigroup’s revenues and net income. The impact of adopting this amendment resulted in a cumulative catch-up reclassification from retained earnings to AOCI of an accumulated after tax loss of approximately $15 million at January 1, 2016. Financial statements for periods prior to 2016 were not subject to restatement under the provisions of this ASU. For additional information, see Note 17, Note 20 and Note 21 to the Consolidated Financial Statements. The Company is evaluating the effect that the other provisions of ASU 2016-01 will have on its Consolidated Financial Statements and related disclosures.

FUTURE APPLICATION OF ACCOUNTING STANDARDS

Income Tax Impact of Intra-Entity Transfers of Assets

In October 2016, the FASB issued ASU No. 2016-16, Income Taxes - Intra-Entity Transfers of Assets Other Than Inventory, which will require an entity to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. The ASU is effective on January 1, 2018 with early adoption permitted. The Company is evaluating the effect that ASU 2016-16 will have on its Consolidated Financial Statements.

Accounting for Financial Instruments-Credit Losses

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326). The ASU introduces a new accounting model, the Current Expected Credit Losses model (CECL), which requires earlier recognition of credit losses, while also providing additional transparency about credit risk.

The FASB’s CECL model utilizes a lifetime “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. The expected credit losses are adjusted each period for changes in expected lifetime credit losses. For available-for-sale securities where fair value is less than cost, credit-related impairment, if any, will be recognized in an allowance for credit losses and adjusted each period for changes in expected credit risk. This model replaces the multiple existing impairment models in current GAAP, which generally require that a loss be incurred before it is recognized.

The CECL model represents a significant departure from existing GAAP, and may result in material changes to the Company’s accounting for financial instruments. The Company is evaluating the effect that ASU 2016-13 will have on its Consolidated Financial Statements and related disclosures. The ASU will be effective for Citi as of January 1, 2020. Early application is permitted for annual periods beginning January 1, 2019.

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. The ASU is not applicable to financial instruments and, therefore, is not expected to impact a majority of the Company’s revenue, including net interest income. The Company plans to adopt the new revenue recognition guidance in the first quarter of 2018. The Company does not expect a material change in timing of revenue recognition and is evaluating the effect that ASU 2014-09 will have on the presentation of its Consolidated Financial Statements and related disclosures and its adoption method.

Lease Accounting

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which is intended to increase transparency and comparability of accounting for lease transactions. The ASU will require lessees to recognize all leases on the balance sheet as lease assets and lease liabilities and will require both quantitative and qualitative disclosures regarding key information about leasing arrangements. Lessor accounting is largely unchanged. The guidance is effective beginning January 1, 2019 with an option to early adopt. The Company is evaluating whether to early adopt and the effect that ASU 2016-02 will have on its Consolidated Financial Statements, regulatory capital and related disclosures.