REGULATORY CAPITAL AND OTHER REGULATORY MATTERS (Details Textual)	Dec. 31, 2012	Dec. 31, 2011
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to total assets, percentage	9.20%	8.37%
Minimum
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to total assets, percentage	7.00%

Tier 1 Capital divided by total assets in accordance with regulatory agreement.

No definition available.

Name:	fbspra_TierOneCapitalToTotalAssets
Namespace Prefix:	fbspra_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant