REGULATORY CAPITAL (Details Textual)	Jun. 30, 2012	Dec. 31, 2011
Tier One Capital to Total Assets	8.79%	8.37%
Minimum [Member]
Tier One Capital to Total Assets	7.00%	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