Securities Sold Under Agreements to Repurchase (Details Textual) (U.S. Government Sponsored Enterprise Securities [Member], USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
U.S. Government Sponsored Enterprise Securities [Member]
Securities Sold Under Agreements to Purchase (Textual) [Abstract]
U.S. Government Sponsored Enterprise securities with a total amortized cost	$ 187,995,000	$ 140,891,000	$ 107,030,000
Fair value of the collateral repurchase agreement	$ 191,704,000	$ 143,212,000	$ 108,200,000

Fair value as of the balance sheet date of the collateral, or portion thereof, that has been re-pledged, delivered, or otherwise used (generally under repurchase agreements, securities lending agreements or to cover short sales).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=7523297&loc=SL6224234-111729

Name:	us-gaap_FairValueOfSecuritiesReceivedAsCollateralThatHaveBeenResoldOrRepledged
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant