REGULATORY CAPITAL (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
First Banks Inc [Member]
Total Capital	$ 87,400	$ 73,830
Total Capital to Risk Weighted Assets	2.33%	1.88%
Total Capital Required for Capital Adequacy	8.00%	8.00%
Tier One Capital	43,700	36,915
Tier One Capital to Risk Weighted Assets	1.16%	0.94%
Tier One Capital Required for Capital Adequacy	4.00%	4.00%
Tier One Leverage Capital	43,700	36,915
Tier One Leverage Capital to Average Assets	0.68%	0.56%
Tier One Leverage Capital Required for Capital Adequacy	4.00%	4.00%
First Bank [Member]
Total Capital	608,776	588,860
Total Capital to Risk Weighted Assets	16.20%	14.98%
Total Capital Required for Capital Adequacy	8.00%	8.00%
Total Capital Required to be Well Capitalized	10.00%	10.00%
Tier One Capital	560,859	538,592
Tier One Capital to Risk Weighted Assets	14.92%	13.70%
Tier One Capital Required for Capital Adequacy	4.00%	4.00%
Tier One Capital Required to be Well Capitalized	6.00%	6.00%
Tier One Leverage Capital	$ 560,859	$ 538,592
Tier One Leverage Capital to Average Assets	8.71%	8.19%
Tier One Leverage Capital Required for Capital Adequacy	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	5.00%	5.00%

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

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