REGULATORY CAPITAL AND OTHER REGULATORY MATTERS (Schedule of Regulatory Capital ) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
First Banks, Inc. (Consolidated) [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital, Amount	$ 582,115	$ 475,312
Total Capital to Risk-Weighted Assets, Ratio	14.88%	12.25%
Total Capital Required for Capital Adequacy, Ratio	8.00%	8.00%
Tier One Capital, Amount	283,962	284,396
Tier One Capital to Risk-Weighted Assets, Ratio	7.26%	7.33%
Tier One Capital Required for Capital Adequacy, Ratio	6.00%	4.00%
Common Equity Tier One Risk Based Capital, Amount	(44,624)
Common Equity Tier One Capital To Risk-Weighted Assets, Ratio	(1.14%)
Common Equity Tier One Capital Required For Capital Adequacy, Ratio	4.50%
Tier One Leverage Capital, Amount	283,962	284,396
Tier One Leverage Capital to Average Assets, Ratio	5.02%	5.01%
Tier One Leverage Capital Required for Capital Adequacy, Ratio	4.00%	4.00%
First Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital, Amount	660,631	691,350
Total Capital to Risk-Weighted Assets, Ratio	16.80%	17.81%
Total Capital Required for Capital Adequacy, Ratio	8.00%	8.00%
Total Capital Required to be Well Capitalized, Ratio	10.00%	10.00%
Tier One Capital, Amount	612,837	642,593
Tier One Capital to Risk-Weighted Assets, Ratio	15.59%	16.55%
Tier One Capital Required for Capital Adequacy, Ratio	6.00%	4.00%
Tier One Capital Required to be Well Capitalized, Ratio	8.00%	6.00%
Common Equity Tier One Risk Based Capital, Amount	612,837
Common Equity Tier One Capital To Risk-Weighted Assets, Ratio	15.59%
Common Equity Tier One Capital Required For Capital Adequacy, Ratio	4.50%
Common Equity Tier One Capital To Be Well Capitalized, Ratio	6.50%
Tier One Leverage Capital, Amount	$ 612,837	$ 642,593
Tier One Leverage Capital to Average Assets, Ratio	10.78%	11.35%
Tier One Leverage Capital Required for Capital Adequacy, Ratio	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized, Ratio	5.00%	5.00%

Common Equity Tier 1 Capital divided by risk weighted assets as defined by regulations.

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Common Equity Tier One Risk Based Capital as defined in the regulations.

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The minimum Common Equity Tier One Capital Ratio (Common Equity Tier 1 Capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Common Equity Tier 1 Capital Ratio (Common Equity 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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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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-Publisher FASB

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

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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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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