Amount of leverage assets as calculated in accordance with U.S. Federal regulatory capital standards.

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Dividends that Citigroup received from Citibank during the current period.

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Risk Weighted Assets, Standardized Approach

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Supplementary Leverage Ratio

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Supplementary Leverage Ratio Required to Be Well Capitalized To Risk Weighted Assets

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Supplementary Leverage Ratio, Stated Minimum

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Tier 1 common capital, as defined by Supervisory Capital Assessment Program by U.S. banking regulators.

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Tier 1 common capital divided by risk weighted assets, as by Supervisory Capital Assessment Program by U.S. banking regulators.

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Tier One Common Capital Required for Capital Adequacy to Risk Weighted Assets

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Tier One Common Equity Capital Required to Be Well Capitalized To Risk Weighted Assets

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Total Leverage Exposure

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of risk-weighted assets as calculated in accordance with U.S. Federal regulatory capital standards.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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REGULATORY CAPITAL - Regulatory Capital Compliance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital ratio, stated minimum	4.50%
Tier 1 Capital ratio, stated minimum	6.00%
Total Capital ratio, stated minimum	8.00%
Tier 1 Leverage ratio, stated minimum	4.00%
Dividends received from Citibank N.A.	$ 13,800	$ 13,500
Citigroup Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital	167,378
Tier 1 Capital	178,387
Total Capital (Tier 1 Capital Tier 2 Capital)	202,146
Total Risk-Weighted Assets	1,166,764
Quarterly Adjusted Average Total Assets	1,768,415
Total Leverage Exposure	$ 2,351,883
Common Equity Tier 1 Capital ratio	14.35%
Tier 1 Capital ratio, well capitalized minimum	6.00%
Tier 1 Capital ratio	15.29%
Total Capital ratio, well capitalized minimum	10.00%
Total Capital ratio	17.33%
Tier 1 Leverage ratio	10.09%
Supplementary leverage ratio	7.58%
Risk-weighted assets, standardized approach	$ 1,126,000
Citibank, N.A.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital	126,277
Tier 1 Capital	126,282
Total Capital (Tier 1 Capital Tier 2 Capital)	138,638
Total Risk-Weighted Assets	973,739
Quarterly Adjusted Average Total Assets	1,332,978
Total Leverage Exposure	$ 1,859,211
Common Equity Tier 1 Capital ratio	12.62%
Common Equity Tier 1 Capital ratio, well capitalized minimum	6.50%
Tier 1 Capital ratio, well capitalized minimum	8.00%
Tier 1 Capital ratio	12.62%
Total Capital ratio, well capitalized minimum	10.00%
Total Capital ratio	14.24%
Tier 1 Leverage ratio	9.47%
Tier 1 Leverage ratio, well capitalized minimum	5.00%
Supplementary leverage ratio	6.79%
Risk-weighted assets, standardized approach	$ 1,001,000
Forecast
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Supplementary leverage ratio, stated minimum			3.00%
Supplementary leverage ratio, well capitalized minimum			6.00%