REGULATORY CAPITAL AND OTHER REGULATORY MATTERS (Details Textual)	Mar. 31, 2013	Dec. 31, 2012
Tier One Capital to Total Assets	9.54%	9.20%
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